Ascorbate affects proliferation of guinea-pig vascular smooth muscle cells by direct and extracellular matrix-mediated effects.
Proliferation of smooth muscle cells and deposition of extracellular matrix proteins are important events in the formation of atherosclerotic plaques. We have investigated the direct and matrix-mediated effects of ascorbate on the proliferation rate of vascular smooth muscle cells (VSMC) isolated from the guinea-pig aorta. In the presence of ascorbate, cells showed a bi-phasic growth pattern. At 125 microM ascorbate, -3H--thymidine incorporation was stimulated 25%. However, higher concentrations of ascorbate gradually decreased cell-incorporated radioactivity up to 50% at 2 mM ascorbate. These effects of ascorbate on DNA synthesis in VSMC were paralleled by the changes in cell number and were not due to ascorbate cytotoxicity. Alpha-tocopherol (0.1 mM), individually and in combinations with 1 mm ascorbate, also inhibited DNA synthesis in VSMC. Ascorbate also influenced proliferation of smooth muscle cells through matrix-mediated effect. New VSMC culture plated on extracellular matrices deposited by smooth muscle cells in the presence of 0.1-1 mM ascorbate had up to 50% lower proliferation rate than on matrices from ascorbate-deficient cells, as assessed by [3H]-thymidine incorporation. This effect was independent from alpha-tocopherol and specific inhibitors of collagen synthesis: L-azetidine-2-carboxylic acid and pyridine-2,4-dicarboxylic acid. An ascorbate-dependent matrix effect was specific for smooth muscle cells grown on VSMC and human skin fibroblast-originated matrices, but not for human vascular endothelial cells. The possible involvement of ascorbate in the regulation of smooth muscle cells proliferation by its antioxidant/pro-oxidant effects and regulation of extracellular matrix composition are discussed.
Ivanov
V O
VO
Linus Pauling Institute of Science, 440 Page Mill Road, Palo Alto, CA 94306, USA.
Ivanova
S V
SV
Niedzwiecki
A
A
D000818:Animals; D001011:Aorta / Q000166:cytology; D001205:Ascorbic Acid / Q000494:pharmacology*; D001383:Azetidinecarboxylic Acid / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005109:Extracellular Matrix / Q000187:drug effects* / Q000378:metabolism; D006168:Guinea Pigs; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects; D011393:Procollagen-Proline Dioxygenase / Q000037:antagonists & inhibitors; D011725:Pyridines / Q000494:pharmacology; D014810:Vitamin E / Q000494:pharmacology
D004791:Enzyme Inhibitors; D011725:Pyridines; D014810:Vitamin E; C055293:2,4-pyridinedicarboxylic acid; D001383:Azetidinecarboxylic Acid; D003094:Collagen; D011393:Procollagen-Proline Dioxygenase; D001205:Ascorbic Acid