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 compared the vasomotor effects of the atherosclerotic lipoprotein, oxidized low-density lipoprotein (LDL), in these tissues. 5-HT-induced contraction and endothelium-dependent relaxation were similar, as was sodium nitroprusside-induced relaxation, in coronary arteries from male and female pigs. These data suggest that there were no gender-related differences in Ei-HT-induced contraction or B-HT-mediated nitric oxide (NO) release from the coronary endothelium. In contrast, oxidized LDL (100 mu g/ml) enhanced Ei-HT-induced contraction to a greater extent in coronary arteries from male versus female pigs. Because oxidized LDL inhibited 5-HT-induced relaxation similarly in arteries from male and female animals, a greater effect of oxidized LDL on agonist-induced NO release in tissues from male pigs cannot explain the greater effect on 5-HT-induced contraction. Oxidized LDL contracted coronary arteries from males with a greater force than arteries from females when measured from baseline tone, suggesting that oxidized LDL inhibited basal NO release to a greater extent in coronary arteries from male pigs compared with females, an effect that may have participated in the greater enhancement of 5-HT-induced contraction that occurred in arteries from male pigs. These gender-related differences in the vasomotor effects of oxidized LDL may play an important role in the lesser incidence of cardiovascular disease in premenopausal females than in males and may provide insight into the cardioprotective effect of estrogen.