Mechanism of action of the inhibitory effect of nifedipine on the growth of cultured aortic cells from spontaneously hypertensive and normotensive rats.

摘要

1. To gain insight into the parameters which control vascular structure, we investigated the mechanisms whereby nifedipine, and other dihydropyridines, inhibit the growth of cultured fibroblasts isolated from the adventitia of the aorta of spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats. 2. The effects of nifedipine on cell proliferation and on serum-induced DNA synthesis were determined by measuring the cell number and the incorporation of [3H]-thymidine, respectively. The mechanism of action of nifedipine was studied by adding the drug either to randomly growing cells or to quiescent, G0/G1 arrested and synchronized cells. The effects of varying the duration of drug treatment were also examined. 3. In randomly growing cultures nifedipine, like other dihydropyridines concentration-dependently inhibited cell proliferation; the rank order of effect (measured at a concentration of 10 microM) was nifedipine > nisoldipine > nitrendipine approximately nimodipine. 4. In G0/G1 arrested cell cultures, nifedipine concentration-dependently inhibited serum-induced [3H]-thymidine incorporation. In this respect it had similar effects in cell cultures from WKY and SHR. In both SHR and WKY cultures, nifedipine delayed the transition from G0/G1 to S phase, and inhibited serum-induced DNA synthesis possibly by acting on the early G1 phase. 5. In cell cultures from both SHR and WKY, serum-induced DNA synthesis was similarly (approximately 40%) inhibited after a 1 day treatment with 10 microM nifedipine. In contrast, after 5 days treatment with the drug, the inhibition of DNA synthesis was approximately 65% and approximately 10% in SHR and WKY cultures, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)