Effects of captopril on platelet cytosolic free Ca2+ concentrations and on suppression of cell proliferation in culture.

In order to investigate the feasibility of angiotensin converting enzyme inhibitors (ACEIs) in preventing the development of atherosclerosis and restenosis after coronary angioplasty and to study their mechanisms, we measured the platelet cytosolic free Ca2+ concentration ([Ca2+]i) and observed the effects of captopril on platelet [Ca2+]i in rabbits and also observed the inhibitive action on fibroblast proliferation in culture. The results showed that resting platelet [Ca2+]i,ADP- or thrombin-stimulated platelet elevation amplitude after administration of captopril (12.5 mg, twice daily) for 15 days were significantly reduced in comparison with those before administration. And captopril also significantly inhibited fibroblast proliferation or reduced 3H-thymidine (3H-TdR) incorporation in culture in a dose-dependent manner. These findings suggest that ACEIs are promising drugs to reduce restenosis incidence after coronary angioplasty and to prevent atherosclerosis as well as provide a new explanation for their effects of suppressing cell proliferation.