INFLUENCE OF GENDER ON VASOMOTOR EFFECTS OF OXIDIZED LOW-DENSITY-LIPOPROTEIN IN PORCINE CORONARY-ARTERIES

This study compared 5-hydroxytryptamine (5-HT)-induced contraction and relaxation in coronary arteries from male and female pigs and compare d the vasomotor effects of the atherosclerotic lipoprotein, oxidized l ow-density lipoprotein (LDL), in these tissues. 5-HT-induced contracti on and endothelium-dependent relaxation were similar, as was sodium ni troprusside-induced relaxation, in coronary arteries from male and fem ale pigs. These data suggest that there were no gender-related differe nces in Ei-HT-induced contraction or B-HT-mediated nitric oxide (NO) r elease from the coronary endothelium. In contrast, oxidized LDL (100 m u g/ml) enhanced Ei-HT-induced contraction to a greater extent in coro nary arteries from male versus female pigs. Because oxidized LDL inhib ited 5-HT-induced relaxation similarly in arteries from male and femal e animals, a greater effect of oxidized LDL on agonist-induced NO rele ase in tissues from male pigs cannot explain the greater effect on 5-H T-induced contraction. Oxidized LDL contracted coronary arteries from males with a greater force than arteries from females when measured fr om baseline tone, suggesting that oxidized LDL inhibited basal NO rele ase to a greater extent in coronary arteries from male pigs compared w ith females, an effect that may have participated in the greater enhan cement of 5-HT-induced contraction that occurred in arteries from male pigs. These gender-related differences in the vasomotor effects of ox idized LDL may play an important role in the lesser incidence of cardi ovascular disease in premenopausal females than in males and may provi de insight into the cardioprotective effect of estrogen.