Characterization of the responses of isolated rings of rabbit left carotid artery. A potential protocol for the assessment of pathologically induced functional changes.

Studies on such injury processes as atherosclerosis, angioplasty, and restenosis, have shown an impairment of relaxations mediated by endothelium-derived relaxing factor (EDRF). Increasingly, the rabbit carotid artery is being used as the vessel of choice in such studies, but a definite protocol for the assessment of endothelial dysfunction or denudation has not been developed. Using isolated carotid artery rings, we have obtained reproducible dose-response curves in endothelially intact and denuded vessels from normally fed rabbits to a variety of vasoconstrictors and endothelium-dependent and -independent vasodilators. Endothelium-dependent vasodilators (acetylcholine (1 x 10(-8)-1 x 10(-6) M), carbachol (1 x 10(-8)-5 x 10(-6) M), substance P (0.01-100 nM), and A23187 (1 x 10(-8)-1 x 10(-7) M) relaxed the arteries in a concentration-dependent manner but produced no relaxation in denuded vessels. Endothelium-independent nitric oxide (NO) donors [Sin-1 (1 x 10(-8)-1 x 10(-6) M)] and sodium nitroprusside (1 x 10(-8)-1 x 10(-6) M)) relaxed both intact and denuded vessels to a similar degree (slight augmentation of the relaxation induced in denuded vessels was not significant), demonstrating that denuded vessels did not have an impaired reactivity to NO. Concentration response curves to the vasoconstrictors [5-HT (1 x 10(-7)-1 x 10(-4) M) and KCl (15-60 mM)] were produced in intact vessels and it was shown that similar contraction was produced by 1 x 10(-6) M 5-HT in intact and denuded vessels. This indicated that the vessels retained contractile ability following denudation.(ABSTRACT TRUNCATED AT 250 WORDS)