Adaptation of Hindquarter Vascular Reactivity to Femoral Artery Ligation and Hypercholesterolemia in the Rabbit

Abstract

Aims: The effects of ischemia and hypercholesterolemia on the function and morphological adaptation of the rabbit hindlimb were assessed. Methods: In rabbits on normal or cholesterol diet, experiments were performed on days 0–28 following bilateral femoral artery ligation. Calf blood pressure (C_BP), exercise tolerance, flow reserve, agonist vasodilatation, angiography and capillary density were examined and modeled. Results: C_BP decreased markedly post-ligation and returned to 41 and 68% of baseline by days 7 and 28. Exercise tolerance was attenuated 40% and flow reserve 50–60% on day 7, with recovery by day 28. Ligation caused decreases in 5-hydroxytryptamine-induced dilatation, while adenosine and acetylcholine responses were unaffected. Hypercholesterolemia attenuated acetylcholine-elicited dilatation. There was marked loss of adenosine dilatation on days 7–14 in the ligation plus hypercholesterolemia group. Ligation caused a doubling in the number of medium-sized collateral arteries. Hypercholesterolemia, either alone or combined with ligation, greatly augmented small vessel density. Capillary density was unaltered by any treatment. Conclusions: The rabbit hindlimb shows a remarkable ability to recover its muscle function through vascular adaptation and remodeling 4 weeks following ligation, with or without hypercholesterolemia. Exercise tolerance, flow reserve and vascular reactivity were mainly restored 28 days post-ligation.