Dipyridamole: an antioxidant that promotes the proliferation of aorta smooth muscle cells.

Smooth muscle cells from guinea pig aorta were grown in tissue culture. Dipyridamole enhanced the proliferation of these cells in culture and dipyridamole overcame the inhibitory effect of arachidonic acid on cell proliferation. Dipyridamole and the antioxidant vitamin E both increased the cloning potential and the number of population doublings for smooth muscle cells in culture. Lipid peroxidation was measured in cultured cells with thiobarbituric acid. Dipyridamole, vitamin E and butylated hydroxytoluene inhibited lipid peroxidation both in cultures treated with media alone and in cultures treated with arachidonic acid. Dipyridamole enhanced PGI2 biosynthesis while vitamin E and butylated hydroxytoluene had no effect on PGI2 biosynthesis. These data show that cell proliferation is related to lipid peroxidation rather than PGI2 biosynthesis. Dipyridamole functions as an antioxidant that stimulates the proliferation of aorta smooth muscle cells.