[An experimental study on the mechanism of antiatherosclerotic effect of nifedipine].

Thirty male N-Z white rabbits were randomized into 3 groups (10 each). Normal control group (C) were fed regular chow. Atherosclerotic control group (CAS) were fed a chow containing 1% cholesterol. Nifedipine group (N) were fed 1% cholesterol chow and nifedipine 40 mg/animal/day. The experiment lasted for 12 weeks. Blood total cholesterol, HDL-C, MDA, 6-keto-PGF1 alpha and TXB2 were measured. After the sacrifice of the animals, electron probe microanalysis was employed to cryo-ultrathin sections of the aorta for measuring cytoplasmic calcium content in situ in the medial smooth muscle cells. The area of atherosclerotic plaques of the aortae was planimetried with computer. The results showed that MDA and TXB2 in group CAS were markedly higher than those in groups C and N (P < 0.01 or 0.05). The cytoplasmic calcium in group CAS was significantly higher than that in groups C and N (P < 0.01). The difference between groups C and N was not significant. The area of atherosclerotic lesions in group CAS was 44 +/- 8%, markedly larger than that in group N (13 +/- 5%, P < 0.01). The antiatherosclerotic effects of nifedipine may be mainly by a mechanism of inhibiting intracellular calcium overload.