The immunoquantification of caveolin-1 and eNOS in human and rabbit diseased blood vessels

In this study, caveolin-1 (cav-1), an inhibitor of endothelial nitric oxide synthase (eNOS), was semi-quantified in diseased human and rabbit blood vessels. New Zealand White rabbits were fed, for 12 weeks, a high methionine diet (to induce intimal hyperplasia), 0.5% cholesterol diet, a normal diet, or the combination of both experimental diets. Excess segments of human internal mammary arteries (IMA) and radial arteries (RA) were obtained from patients undergoing coronary artery bypass surgery. eNOS and cav-1 were localized throughout both human and rabbit vessels. In rabbit arteries, eNOS was significantly increased in the endothelium overlying intimal thickening and atherosclerotic plaques compared with the adjacent endothelium overlying normal media. Interestingly, the endothelial cav-1:eNOS ratio increased 5-fold only in endothelium overlying plaques but decreased in endothelium overlying vessels with neo-intimal thickening. In human tissue, there was no difference between RA and IMA eNOS immunoreactivity in endothelium, intima, or media; however, RA endothelial, intimal, and medial cav-1 immunoreactivity increased 4-fold (p<0.02), 8-fold (p<0.001), and 4-fold (p<0.004), respectively, compared with IMA. Furthermore, the cav-1:eNOS immunostaining ratio in the media correlated with intimal thickening (r2 = 0.5). Our results suggest a close relationship between increased cav-1 and diseased blood vessels.