COUNTERACTING THE INHIBITION OF COLLAGEN SYNTHESIS BY SELECT CALCIUM AND SODIUM CHANNEL BLOCKERS USING ASCORBIC ACID AND ASCORBYL PALMITATE

Abstract

A therapeutic use of ascorbyl palmitate, ascorbic acid and/or derivatives thereof to reverse or counter the adverse effects of channel blockers in the medical management of cardiovascular disease in a subject is presented. Effects of select Na- and Ca-channel blockers on collagen synthesis and deposition were evaluated in cultured human dermal fibroblasts and aortic smooth muscle cells by immunoassay. Ca and Na-channel blockers inhibited the synthesis of collagen type I and collagen type IV, the basic molecules of vascular wall stability. The inhibitory effects of the calcium and sodium channel blockers on collagen synthesis was reversed by introducing ascorbic acid and/or ascorbyl palmitate. It can be concluded that calcium and sodium channel blockers have a direct inhibitory effect on collagen synthesis, favoring the instability of the vascular wall and the progression of cardiovascular disease, an effect that is mitigated by treatment with, ascorbyl palmitate, ascorbic acid and or derivatives thereof.

Claims

1. A method of increasing an ascorbate dependent-ECM deposition of collagen type I and IV, comprising: administering an ascorbate as an adjunct therapy to increase the ascorbate dependent-ECM deposition of collagen type I and IV synthesis in an intracellular milieu and extra cellular matrix of the subject having a disease and treated by a calcium channel blocker, a sodium channel blocker and a combination thereof.

2. The method of claim 1, wherein the calcium channel blocker, the sodium channel blocker and the combination thereof is at least one of the following: a) Capsaicin, a natural sodium channel blocker; b) Lidocaine, a sodium channel blocker; c) Quinidine, a sodium channel blocker; d) Ditiazem, a calcium channel blocker; e) Nifedipine, a calcium channel blocker; and f) Verapamil, a calcium channel blocker.

3. The method of claim 1, wherein the ascorbate is in form of ascorbic acid.

4. The method of claim 1, wherein the ascorbate is in form of calcium ascorbate, magnesium ascorbate, another form of mineral ascorbate or a combination thereof.

5. The method of claim 1, wherein the ascorbate is in form of an ascorbyl palmitate or another fat soluble form of ascorbate

6. The method of claim 1, wherein the ascorbate is any combination of the ascorbate forms of claims 3 to 5.

7. A method of countering an inhibition of collagen type I and IV synthesis in a subject suffering from a disease due to usage of a channel blocker, comprising: administering an ascorbate to the subject as an adjunct treatment with the channel Mocker; wherein the channel blocker is at least one of a calcium channel blocker, the sodium channel blocker and the combination thereof;

8. A method according to claim 7 where the disease includes the prevention and/or treatment of hypertension.

9. A method according to claim 1 where the disease includes the prevention and/or treatment of arrhythmia.

10. A method according to claim 7 where the disease includes the prevention and/or treatment of coronary artery disease, cerebrovascular disease or any other form of occlusive vascular disease

11. A method according to claim 7 where the disease includes the prevention and/or treatment of angina pectoris.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0019] Example embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:

[0020] FIG. 1A illustrates the effects of capsaicin (natural Na.sup.+ blocker) on collagen type I ECM deposition by cultured human skin fibroblasts. (* indicates the significance of p≦0.005 between ascorbate and ascorbate+ capsaicin ECM collagen 1 deposition)

[0021] FIG. 1B illustrates the effects of ditiazem (Ca.sup.++ blocker) on collagen type I ECM deposition by human skin fibroblasts (* indicates significance of p≦0.0001 between ascorbate vs. ascorbate and ditiazem ECM collagen 1 deposition)

[0022] FIG. 1C illustrates the effects of lidocaine (Na.sup.+ blocker) on collagen type I ECM deposition by cultured human skin fibroblasts. (* indicates the significance of p≦0.0001 between ascorbate and ascorbate+lidocaine ECM collagen 1 deposition; ** indicates significance of p≦0.01 between ECM collagen 1 deposition at increased concentrations of lidocaine compared to control)

[0023] FIG. 1D illustrates the effects of nifedipine (Ca.sup.++ blocker) on collagen type I ECM deposition by cultured human skin fibroblasts. (* indicates the significance of p<0.0001 between ascorbate and ascorbate+nifedipine ECM collagen 1 deposition; ** indicates significance of p≦0.05 between ECM collagen 1 deposition at increased concentrations of nifedipine compared to control)

[0024] FIG. 1E illustrates the effects of quinidine (Na.sup.+ blocker) on collagen type I ECM deposition by cultured human skin fibroblast. (* indicates the significance of p≦0.006 between ascorbate and ascorbate+quinidine ECM collagen 1 deposition)

[0025] FIG. 1F illustrates the effects of verapamil (Ca.sup.++ blocker) on collagen type I ECM deposition by cultured human skin fibroblasts. (* indicates the significance of p≦0.002 between ascorbate and ascorbate+verapamil ECM collagen 1 deposition)

[0026] FIG. 2A illustrates the effects of 50 μM nifedipine on ascorbic acid dependent ECM deposition of collagen type I by cultured AoSMC (* indicates the significance of p≦0.02 between ascorbate and ascorbate+nifedipine ECM collagen 1 deposition)

[0027] FIG. 2B illustrates the Effects of 50 μM nifedipine on ascorbyl palmitate dependent-ECM deposition of collagen type I by cultured AoSMC. (* indicates the significance of p≦0.045 between ascorbyl palmitate and ascorbyl palmitate+nifedipine ECM collagen 1 deposition)

[0028] FIG. 2C illustrates the effects of 50 μM nifedipine on ascorbic acid dependent ECM deposition of collagen type IV by AoSMC. (* indicates the significance of p≦0.02 between ascorbate and ascorbate+nifedipine ECM collagen IV deposition)

[0029] FIG. 2D illustrates the effects of 50 μM nifedipine on ascorbyl palmitate dependent ECM deposition of collagen type IV by AoSMC. (* indicates the significance of p≦0.02 between ascorbyl palmitate and ascorbyl palmitate+nifedipine ECM collagen IV deposition)

[0030] FIG. 3A illustrates the effects of ascorbic acid on intracellular content of collagen type I in AoSMC in the presence or absence of 50 μM nifedipine. (* indicates the significance of p≦0.002 between ascorbic acid or ascorbyl palmitate alone vs. with nifedipine on intracellular content of collagen type 1)

[0031] FIG. 3B illustrates the effects of ascorbic acid on intracellular content of beta-Actin in AoSMC in the presence or absence of 50 μM nifedipine. (* indicates the significance of p≦0.03 between ascorbic acid or ascorbyl palmitate alone vs. with nifedipine on intracellular content of beta actin)

[0032] FIG. 3C illustrates the effects of ascorbic acid on intracellular content of collagen type I in AoSMC in the presence or absence of 50 μM nifedipine. Collagen type I content was normalized by beta actin content in corresponding samples. (* indicates the significance of p≦0.003 between ascorbic acid alone vs. with nifedipine on intracellular content of collagen type 1)

[0033] FIG. 4 illustrates the effects of nifedipine 50 μM on ascorbate accumulation inside human AoSMC. (* indicates the significance of p≦0.06 between ascorbic acid or ascorbyl palmitate alone vs. with nifedipine on intracellular ascorbate content)

[0034] Others features of the present embodiments will be apparent from the accompanying drawings and from the detailed description that follows.

DETAILED DESCRIPTION

[0035] The following embodiments are described for illustrative purposes only with reference to the Figures. Those of skill in the art will appreciate that the following description is exemplary in nature, and that various modifications to the parameters set forth herein could be made without departing from the scope of the present invention. It is intended that the specification and examples be considered as examples only. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

[0036] In order to provide a clear and consistent understanding of the terms used in the present disclosure, a number of definitions are provided below. Moreover, unless defined otherwise, all technical and scientific terms as used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure pertains. The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the description may mean “one”, but it is also consistent with the meaning of “one or more”, “at least one”, and “one or more than one”. Similarly, the word “another” may mean at least a second or more. As used herein, the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “include” and “includes”) or “containing” (and any form of containing, such as “contain” and “contains”), are inclusive or open-ended and do not exclude additional, unmentioned elements or process steps. As used herein, when referring to numerical values or percentages, the term “about” includes variations due to the methods used to determine the values or percentages, statistical variance and human error. Moreover, each numerical parameter in this application should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. The making and using of the presently preferred embodiments are discussed in detail below. It should be appreciated, however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.

[0037] Heart disease is the leading cause of death for both men and women. Arrhythmia is a kind of heart disease, wherein there is a problem with the rate or rhythm of the heartbeat. The term “arrhythmia” refers to any change from the normal sequence of electrical impulses. The electrical impulses may happen too fast, too slowly, or erratically thereby causing the heart to beat too fast, too slowly, or erratically. In the case where the heart does not beat properly, it cannot pump blood effectively, which leads to improper functioning of the lungs, brain and all other organs and they may eventually shut down or be damaged. Arrhythmias are an abnormality of the rate or rhythm of the heartbeat, such as atrial fibrillation, atrial flutter, ventricular fibrillation and ventricular tachycardia, which can lead to sudden cardiac arrest. Sudden cardiac arrest is the abrupt loss of heart function in a person who may or may not have diagnosed heart disease. The time and mode of death are unexpected. It occurs instantly or shortly after the symptoms appear.

[0038] Antiarrhythmic agents are pharmaceuticals used to combat cardiac arrhythmias and a variety of antiarrhythmic agents are employed to manage cardiac pathologies. Antiarrhythmic agents are often classed into five main groups according to their mechanism of action, using the Vaughan-Williams classification. Many of the agents however, that fall in the five groups, have considerable overlap in their pharmacologic properties.

[0039] Ascorbic acid is involved in many physiological functions in living organisms. Its role in the synthesis of collagen in connective tissues is well known. The absence of wound healing and the failure of fractures to repair are classically recognized features of scurvy. These features are attributable to impaired collagen formation due to lack of vitamin C. Dr. Rath [9] proposed that heart disease is an early form of scurvy, a condition that increases the needs for biological repair of weakened arterial walls due to impaired collagen synthesis in the body. Ascorbic acid is involved in the metabolism of several amino acids, leading to the formation of hydroxyproline, hydroxylysine, norepinephrine, serotonin, homogenistic acid, and carnitine. Hydroxyproline and hydroxylysine are components of collagens, the fibrous connective tissue in animals. Collagens are principal components of tendons, ligaments, skin, bone, teeth, cartilage, heart valves, intervertebral disks, cornea, eye lens, and the ground substances between cells. Ascorbic acid is essential for the hydroxylation of lysine and proline, a precondition for optimum crosslinking of collagen and elastin and, thus, for maintaining the integrity of the vascular wall. When collagen is synthesized, proline and lysine are hydroxylated to hydroxyproline and hydroxylysine, which are required for the formation of a stable extracellular matrix and cross-links in the collagen fibers. The subsequent triple helix quaternary state of physiologically effective collagen can only be achieved if the requisite proline and lysine residues have been hydroxylated. A deficiency of ascorbic acid reduces the activity of two mixed-function oxidases, prolylhydroxylase and lysyl hydroxylase, which hydroxylate proline and lysine. Some collagen does form in the absence of ascorbic acid, but the fibers are abnormal, resulting in skin lesions and blood vessel fragility, characteristics of scurvy. The major pathway of ascorbic acid cellular uptake is dependent on ion-channel dependent transporters. Therefore, the objective in this study was to evaluate possible interference of select channel blockers on intracellular accumulation and cellular functions of ascorbate in relation to extracellular matrix (ECM) formation. Effects of select Na.sup.+ and Ca.sup.2+ channel blockers on collagen synthesis and deposition were evaluated in cultured human dermal fibroblasts and aortic smooth muscle cells by immunoassay.

Materials and Methods

[0040] All reagents were from Sigma-Aldrich (St. Louis, Mo.) except when indicated differently. Normal human dermal fibroblasts (DF) were supplied by ATCC (Manassas, Va.). Human aortic smooth muscle cells (AoSMC) were purchased from Cambrix (East Rutherford, N.J.). Both cell cultures were maintained in DMEM medium (ATCC) containing antibiotics and 5% fetal bovine serum (FBS, ATCC). All cell cultures were maintained at 37° C. and 5% CO.sub.2 atmosphere. Cell viability was monitored with MTT assay. None of the used experimental conditions resulted in statistically significant cell death (data not shown).

[0041] Collagen production by human cultured cells: In the case of these experiments, DF or AoSMC, at 5th to 8th passages, were seeded on collagen type I-covered plastic plates (Becton-Dickinson, collagen I isolated from rat tail tendon) at density of 25,000/cm.sup.2 and grown to confluence for 5-7 days. For intracellular immunoassay experiments, plain plastic 96-well plates were used. Tested compounds were added to cells at indicated concentrations for 72 h in DMEM supplemented with 2% FBS and cell-produced extracellular matrix was exposed by sequential treatment with 0.5% Triton X100 and 20 mM ammonium sulfate in phosphate buffered saline (PBS, Life Technologies) for 3 min each at room temperature [11]. After four washes with PBS, ECM layers were treated with 1% bovine serum albumin (BSA) in PBS for one hour at room temperature and immediately used in experiments. Alternatively, cell layers were washed three times with PBS and fixed with 3% formaldehyde in PBS at 4° C. for one hour. Fixed cell layers were washed four times with PBS and treated with 1% BSA/PBS for one hour at room temperature.

[0042] Collagen and beta-actin immunoassays: Immunoassays were done [12] by sequential incubation with primary monoclonal antibodies specific to human collagen type I or IV or human beta-actin in 1% BSA/PBS for 2 hours followed by 1 hour incubation with secondary goat anti-mouse IgG antibodies labeled with horse radish peroxidase (HRP). Retained peroxidase activity was measured after the last washing cycle (three times with 0.1% BSA/PBS) using TMB peroxidase substrate reagent (Rockland). Optical density was read with plate reader (Molecular Devices) at 450 nm and expressed as a percentage of control cell samples incubated in un-supplemented 1% BSA/DMEM.

[0043] Intracellular ascorbic acid assay: AoSMC cultures were seeded and grown to confluent layers in plastic 24-well plates (Becton-Dickinson) and treated with nifedipine and ascorbates for 90 min as described above. Intracellular ascorbic acid was extracted as described by Lane and Lawen [13]. Cells were washed briefly three times with ice-cold PBS on ice and incubated with 300 μl of 0.1% saponin in 1% ethanol in PBS for 10 min on an orbit mixer. Samples were collected to Eppendorf tubes and centrifuged at 13,000×g for 5 min. Supernatants were used in an ascorbic acid assay (Ascorbic Acid Colorimetric Assay Kit II FRASC, BioVision) in accordance with the manufacturer's protocol.

[0044] Statistical analysis: Results in figures are means±SD from three or more repetitions from the more representative of at least two independent experiments. Differences between samples were estimated with a two-tailed Student's t-test using MedCalc software (Mariakerke, Belgium) and accepted as significant at p levels less than 0.05.

[0045] Effect of channel blockers and ascorbate on collagen type I ECM deposition by fibroblasts: The results presented in the FIGS. 1A to 1F show one embodiment of this invention wherein all the channel blockers tested inhibited collagen type I deposition to the ECM in the human skin fibroblasts culture however, each one of them do so to a different degree. In another embodiment of this invention it is disclosed that in the presence of ascorbic acid the ECM deposition of collagen I is significantly increased. Among the tested channel blockers, capsaicin demonstrated slight, insignificant inhibition of collagen type I. However, in the presence of 50 μM of ascorbate the collagen I deposition significantly increased (164%-219%, p≦0.0005) at each concentration of capsaicin compared to the level of collagen I deposited under capsaicin without ascorbate.

[0046] In one embodiment of this invention, as presented in FIG. 1B ditiazem showed up to 13.1% inhibition of collagen type I, but this difference did not reach statistical significance. Trend line R.sup.2=0.5045. However, in another embodiment of this invention it was shown that in the presence of 50 μM ascorbate, collagen I deposition significantly increased from 206% to 266%, (p≦0.0001) at each concentration of ditiazem compared to the level of collagen I deposited under ditiazem without ascorbate.

[0047] In one embodiment of this invention, as presented in FIG. 1C it is shown that in the presence of lidocaine there was significant (19.3%-23.7%, p≦0.01) inhibition of collagen type I, trend line R.sup.2=0.4756. In another embodiment of this invention, it is seen that treatment with 50 μM ascorbate resulted in a significant increase of collagen I, from 237% to 258% (p≦0.0001), at each concentration of lidocaine compared to the level of collagen I deposited under lidocaine only.

[0048] In one embodiment of this invention, the effects of nifedipine on collagen type I deposition to the ECM in the human skin fibroblasts culture are presented on FIG. 1D. They show a significant (13%-20.3% (p≦0.05) inhibition of collagen type I, (except when 100 μM concentrations were used), trend line R.sup.2=0.3628. In another embodiment of this invention it is shown that in the presence of 50 μM ascorbate there was a significant increase of collagen type I deposition to the ECM in the human skin fibroblasts culture (117%-244%, p≦0.0001) at each concentration of nifedipine compared to the level of collagen I deposited under nifedipine without ascorbate. This effect of nifedipine on collagen type I deposition to the ECM in the human skin fibroblasts culture is shown in FIG. 1D.

[0049] In one embodiment of this invention it is shown that in the presence of quinidine there was 6% to 12.2% inhibition of collagen type I but the difference did not reach statistical significance, trend line R.sup.2=0.2047 as seen in FIG. 1E. In another embodiment of this invention it is seen that by including ascorbate at 50 μM concentration, there was a significant increase of collagen I deposition to the ECM in the human skin fibroblasts culture (137%-217%, p≦0.006) at each concentration of quinidine compared to the level of collagen I deposited under quinidine without ascorbate.

[0050] In one embodiment of this invention as shown in FIG. 1F it is observed that in the presence of verapamil there was 5.6% to 15.5% inhibition of collagen type I by this calcium channel blocker, but the difference did not reach statistical significance, trend line R.sup.2=0.5383. In another embodiment of this invention it is seen that by including 50 μM ascorbate the collagen type I deposition to the ECM in the human skin fibroblasts culture significantly increased (137%-224%, p≦0.002) at each concentration of verapamil compared to the level of collagen I deposited under verapamil without ascorbate.

[0051] Effect of nifedipine, ascorbic acid and ascorbyl palmitate on collagen types I and IV deposition by cultured human aortic smooth muscle cells (AoSMC): In one embodiment of this invention nifedipine, a representative member of the drugs of the channel blockers class had similar effects on ascorbic acid dependent collagen type I and type IV deposition in AoSMC as it did in human skin fibroblast culture. In another embodiment of this invention comparable results were obtained with verapamil and quinidine (not shown). In one embodiment of this invention as presented in FIG. 2A, 50 μM nifedipine significantly reduced ascorbic acid dependent deposition of collagen type 1 to the ECM in the aortic smooth muscle cells culture: 62.3% (p=0.0001), 41.8% (p=0.019) and 16.5% (p=0.177) at 25, 100 and 400 μM ascorbic acid, respectively. Trend line for ascorbic acid with nifedipine R.sup.2=0.995. It is observed that ascorbic acid at 100 and 400 μM increased the ECM deposition by 114% and 176%, respectively, compared to 25 μM ascorbic acid. Trend line R.sup.2=0.2512. In another embodiment of this invention it is observed that 50 μM nifedipine significantly reduced ascorbyl palmitate dependent deposition of collagen type 1 to the ECM in the aortic smooth muscle cells culture: 25% (p=0.005), 38% (p=0.006), 27.5% (p=0.045), 11% (p=0.154) and 26.5% (p=0.0025) at 1.25, 2.5, 5, 10 and 20 μM ascorbyl palmitate, respectively, as shown in FIG. 2B. Trend line for ascorbyl palmitate with nifedipine R.sup.2=0.7695. It is observed that ascorbyl palmitate administered individually increased ECM deposition by 135% (p=0.013), 189% (p=0.004), 184% (p=0.0013) and 212% (p≦0.0001) at 2.5, 5, 10 and 20 μM, respectively, compared to 1.25 μM ascorbyl palmitate. Trend line R.sup.2=0.90.

[0052] As presented in FIG. 2C, in the presence of 50 μM nifedipine the ascorbic acid dependent deposition of collagen type IV to the ECM in the aortic smooth muscle cells culture was significantly reduced: 36% (p=0.0029), 54% (p=0.021) and 43% (p=0.02) at 25, 100 and 400 μM ascorbic acid, respectively. Trend line for ascorbic acid with nifedipine R.sup.2=0.9982. Ascorbic acid showed increased collagen IV ECM deposition by 175% (p=0.053) and 166% (p=0.0265) at 100 and 400 μM, respectively, compared to 25 μM ascorbic acid, trend line R.sup.2=0.652.

[0053] FIG. 2D shows the effects of 50 μM nifedipine on ascorbyl palmitate dependent ECM deposition of collagen type IV to the ECM in the aortic smooth muscle cells. The results show a significant decrease in collagen IV to 23.5% (p=0.0459), 22.7% (p=0.0228), 22% (p=0.139), 13.5% (p=0.093) and 31.6% (p=0.0055) at 1.25, 2.5, 5, 10 and 20 μM ascorbyl palmitate, respectively. Trend line for ascorbyl palmitate with nifedipine R.sup.2=0.8332. Ascorbyl palmitate alone showed increased collagen IV deposition: 113% (p=0.228), 144% (p=0.068), 138% (p=0.023) and 168% (p=0.004) at 2.5, 5, 10 and 20 μM, respectively, compared to 1.25 μM ascorbyl palmitate, trend line R.sup.2=0.8976.

[0054] Effect of nifedipine on ascorbate-dependent stimulation of collagen type I synthesis in AoSMC: In these experiments the intracellular collagen content was evaluated in relation to the levels of housekeeping intracellular protein, beta-actin. As shown in FIG. 3A, 50 μM nifedipine significantly reduced ascorbate-dependent intracellular collagen type 1 synthesis by cultured aortic smooth muscle cells, by 61% (p=0.0002) and 49.1% (p=0.0005) at 25 and 100 μM ascorbic acid, respectively. In the presence of 400 μM ascorbic acid and nifedipine the intracellular collagen I increased by 122% (p=0.0195) compared to control. In the presence of ascorbyl palmitate at 5 and 20 nifedipine significantly reduced ascorbate-dependent collagen type 1 synthesis by 20.3% (p=0.0002) and 38% (p=0.002), respectively. Trend line for ascorbic acid with nifedipine R.sup.2=0.638 and for ascorbyl palmitate with nifedipine R.sup.2=0.9056. Trend line for ascorbic acid effect alone on collagen I intracellular content was R.sup.2=0.874 and that for ascorbyl palmitate alone was R.sup.2=0.985.

[0055] Nifedipine (50 μM) significantly reduced ascorbate-dependent beta-actin intracellular content in cultured aortic smooth muscle cells compared to control: 29%% (p=0.0018), 22.6% (p=0.0061) and 5% (p=0.54) at 25, 100 and 400 μM ascorbic acid, respectively, as shown in FIG. 3B. In the presence of 5 μM and 20 μM of ascorbyl palmitate nifedipine significantly reduced intracellular beta actin content by 22% (p=0.013) and 23.6% (p=0.033), respectively. Trend line for ascorbic acid with nifedipine R.sup.2=0.5157 and for ascorbyl palmitate with nifedipine R.sup.2=0.8088. Trend line for ascorbic acid effect alone on collagen I intracellular content was R.sup.2=0.5157 and that for ascorbyl palmitate alone was R.sup.2=0.914.

[0056] In the presence of 50 μM nifedipine and ascorbate the intracellular content of collagen type I normalized to beta actin content in aortic smooth muscle cells was reduced compared to the control: 46% (p=0.0005) and 34.4% (p=0.0033) at 25 and 100 μM ascorbic acid, respectively as shown in FIG. 3C. In the presence of 400 μM ascorbic acid nifedipine increased collagen I by 23% (p=0.017) compared to control. However, nifedipine had no significant effect on collagen I content in the presence of ascorbyl palmitate at 5 μM and 20 μM concentrations. Trend line for ascorbic acid with nifedipine R.sup.2=0.871 and for ascorbyl palmitate with nifedipine R.sup.2=0.9918. Trend line for ascorbic acid effect alone on collagen I intracellular content was R.sup.2=0.6396 and that for ascorbyl palmitate alone was R.sup.2=0.9442.

[0057] Effect of nifedipine on intracellular accumulation of ascorbic acid in AoSMC: Nifedipine (50 μM) had an inhibitory effect on intracellular accumulation of ascorbate in cultured aortic smooth muscle cells compared to the control. As shown in FIG. 4, in the presence of 100 μM ascorbic acid, nifedipine decreased intracellular ascorbate by 61.5% (p=0.161) but this difference did not reach statistical significance. However, at 400 μM ascorbic acid, nifedipine significantly reduced (67.7%, p=0.0337) ascorbate intracellular content. However, nifedipine had no significant effect on intracellular ascorbate levels in the cells incubated with ascorbyl palmitate. It was observed that, supplementation with 20 ascorbyl palmitate resulted in significantly higher (10×, P<0.0001) intracellular levels of ascorbic acid compared to the highest concentrations of ascorbic acid used in experiments, which was 400 Ascorbyl palmitate levels higher than 20 μM were found to be cytotoxic to cultured fibroblasts and smooth muscle cells under the experimental conditions (data not shown).

[0058] All channel blockers tested demonstrated inhibitory effects on collagen type I deposition to the ECM by fibroblasts, each to a different degree. Ascorbic acid significantly increased collagen Type I ECM deposition. Nifedipine, a representative member of the channel blockers class, displayed similar effects on ascorbic acid and on ascorbyl palmitate dependent collagen Type I deposition by AoSMC and by human dermal fibroblasts. Furthermore, nifedipine demonstrated significant inhibition of collagen IV ECM deposition.

[0059] By determining intracellular collagen content in relation to the levels of housekeeping intracellular protein beta-actin, it was found that nifedipine counteracted ascorbate-dependent stimulation of collagen type I synthesis in AoSMC. Thus, changes in ECM deposition of collagen seen in previous experiments were caused by its decreased intracellular accumulation (synthesis/protein expression). Nifedipine (50 μM) reduced ascorbate intracellular accumulation in cultured aortic smooth muscle cells compared to the control under water-soluble ascorbic acid as well as lipid soluble ascorbyl palmitate OR ANY OTHER FORM OF ASCORBATE THAT IS FAT SOLUBLE. It was observed that decreased collagen deposition by this channel blocker could be rescued by supplementation of AoSMC with increased levels of ascorbic acid or with ascorbyl palmitate.

[0060] These results confirm the adverse effects of channel blockers on collagen type I and collagen type IV ECM deposition. Ascorbate supplementation could reverse the inhibition of these critical ECM components necessary for maintaining optimal structural integrity of the arterial wall. Ascorbic acid is essential for the hydroxylation of lysine and proline, a precondition for optimum crosslinking of collagen and elastin and, thus, for maintaining the integrity of the vascular wall [9, 14]. As mentioned earlier, Ca.sup.2+ channel blockers such as verapamil, ditiazem and others were shown to significantly decrease collagen deposition in the ECM in human vascular smooth muscle cells and human dermal fibroblasts. These drugs inhibited the expression of fibrillary collagens type I and II and of basement membrane collagen type IV and increased the proteolytic activity of the 72-kDa type IV collagenase [8].

[0061] As in human scurvy, complete dietary ascorbate deprivation has been shown to cause marked alteration in the structural integrity of vascular connective tissue [10, 15, 16]. In a previous study, it was found that hyposcorbemic Gulo−/− mice developed early atherosclerosis accompanied by the deposition of Lp(a) in the intima and deeper layers of the vascular wall, while age-matched mice with high amounts of dietary ascorbate supplementation did not develop atherosclerosis and no Lp(a) detectable in the vascular wall [10]. Disruption of the endothelial layer, impairment of the basement membrane and the structural disintegration of the ECM paralleled the development of scurvy [15]. Since channel blockers have been shown to decrease ascorbate-dependent collagen I and IV, use of channel blockers can lead to increased probability of development of atherosclerosis.

[0062] Regular intake of ascorbic acid results in a variable absorption rate between 70 to 95%, with the degree of absorption decreasing as intake increases [17]. Fractional human absorption of ascorbic acid may be as low as 33% at high intake (1.25 g), but it can reach 98% at low intake (<200 mg) [17]. Ascorbate concentrations over renal re-absorption threshold pass freely into the urine and are excreted. At high dietary doses (corresponding to several hundred mg/day in humans) ascorbate is accumulated in the body until the plasma levels reach the renal resorption threshold, which is about 1.5 mg/dL in men and 1.3 mg/dL in women [18]. Ascorbate at concentrations in the plasma larger than this value (thought to represent body saturation) is rapidly excreted in the urine with a half-life of about 30 minutes. Concentrations less than this threshold value are actively retained by the kidneys, and the excretion half-life for the remainder of the vitamin C store in the body thus increases greatly, with the half-life lengthening as the body stores are depleted. This half-life rises until it is as long as 83 days by the onset of the first symptoms of scurvy [18].

[0063] Ascorbic acid is absorbed in the body by both active transport and simple diffusion. Sodium-dependent active transport—sodium-ascorbate co-transporters (SVCTs) and hexose transporters (GLUTs)—are the two transporters required for absorption. SVCT1 and SVCT2 import the reduced form of ascorbate across plasma membrane [19]. GLUT1 and GLUT3 are the two glucose transporters, and transfer only the dehydroascorbic acid form of ascorbic acid [20]. Although dehydroascorbic acid is absorbed at a higher rate than ascorbate, the amount of dehydroascorbic acid found in plasma and tissues under normal conditions is low, as cells rapidly reduce dehydroascorbic acid to ascorbate [21, 22]. Thus, SVCTs appear to be the predominant system for vitamin C transport in the body. Possible mechanism of ascorbate rescuing effect on channel blocker induced inhibition could be due to competitive inhibition of channel blockers. These conclusions are supported by the rescuing action of increased levels of ascorbate supplementation in channel blocker-dependent inhibition of collagen deposition. Kuo et al. [23] reported that hydrophobic 1,4-dihydropyridine compounds (nifedipine and nicardipine) inhibited Na.sup.+-dependent and Na.sup.+-independent (K.sup.+ substituting Na.sup.+) accumulation of ascorbic acid in human intestinal Caco-2 cells. Ebersole and Molinoff report that ascorbate inhibits binding of dihydropyridine calcium channel blockers [24]. A study by Grossmann et al. demonstrated that co-infusion of ascorbate and quinidine (K+ blocker) abolished ascorbate-dependent venodilation in human veins [25]. The instant disclosure shows that a method of counteracting an inhibition of collagen synthesis in a subject suffering from cardiovascular disease and taking prescribed amount of at least one of a calcium channel blocker, a sodium channel blocker and a combination thereof, and administering an effective amount of an ascorbate as an adjunct therapy to increase the collagen synthesis in an intracellular and extra cellular matrix of the subject. It is evident that adjunct therapy with ascorbate such as ascorbic acid and/or ascorbyl palmitate will not only increase collagen production and maintain the internal and external milieu of the subject cardiovascular health but also counter the negative effect of the channel blockers for the subject who is human.

[0064] The absence of inhibitory effects of channel blockers on ascorbyl palmitate dependent synthesis, ECM deposition of collagen and on accumulation of intracellular ascorbate from channel blockers apparently could be explained by different pathways of intracellular uptake independent from ion-channel-associated transporters, i.e. through hydrophobic portions of the cellular membrane.

[0065] It has been proposed that heart disease is an early form of scurvy, a condition that increases the need for biological repair of weakened arterial walls due to impaired collagen synthesis in the body. Ascorbic acid is essential for the hydroxylation of lysine and proline, a precondition for optimum crosslinking of collagen and elastin and, thus, for maintaining the integrity of the vascular wall. The major pathway of ascorbic acid cellular uptake is dependent on ion-channel dependent transporters.

[0066] Therefore, the objective in this study was to evaluate possible interference of select channel blockers on intracellular accumulation and cellular functions of ascorbate in relation to extracellular matrix (ECM) formation. Effects of select Na- and Ca-channel blockers on collagen synthesis and deposition were evaluated in cultured human dermal fibroblasts and aortic smooth muscle cells by immunoassay. Collagen type I and collagen type IV formation were decreased by the calcium and sodium channel blockers showing inhibition of collagen synthesis. The inhibitory effects of the calcium and sodium channel blockers on percent collagen synthesis was reversed by introducing ascorbic acid and ascorbyl palmitate in the cell culture. Sodium [Na] and calcium [Ca] channel blockers are used in the prevention, treatment and symptom management of various forms of cardiovascular diseases including hypertension, arrhythmia, coronary artery disease as well as other forms of occlusive cardiovascular disease. From this study, it can be concluded that calcium and sodium channel blockers have a direct inhibitory effect on collagen synthesis, which is mitigated by treatment with ascorbic acid and ascorbyl palmitate.

[0067] These studies confirm the adverse effects of channel blockers on collagen type I and type IV deposition, which are the key ECM components essential for maintaining optimal structural integrity of the arterial walls. Ascorbate supplementation reversed channel blocker inhibition of these collagen types synthesis and deposition. The results of this study imply the benefits of ascorbate and ascorbate palmitate supplementation in medical management of cardiovascular disease in order to compensate for adverse effects of channel blockers.

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