Evidence for Impaired Endothelium Dependent Vasodilation in Experimental Left Ventricular Dysfunction

1. The full range of vascular reactivity was investigated in the hindlimb circulation of conscious, autonomically blocked rabbits with experimental (adriamycin-induced) cardiomyopathy. 2. Adriamycin treatment caused a significant reduction in left ventricular systolic function, as assessed by echocardiography (left ventricular fractional shortening, controls vs adriamycin treatment; 36.7 +/- 1.7% vs 27.3 +/- 2.6%, P < 0.05). 3. Under pharmacological autonomic effector block, the range of the vasodilator response (resistance range, from resting to full vasodilatation) to acetylcholine was reduced by 41% (P < 0.05) and by 37% for adenosine (P < 0.05). Despite these changes the sensitivity (ED50) of the responses were unaltered. 4. The ED50 of constrictor responses to noradrenaline and angiotensin II were similarly unaltered, in conjunction with a non-significant attenuation of the constrictor-response range. 5. These results suggest that in this model of experimental left ventricular dysfunction, the capacity of the hindlimb circulation to respond to regionally infused endothelium dependent vasodilators is attenuated.