The vasodilatory response is known to be diminished in chronic
heart failure. In the present study, we used dogs with chronic
heart failure to investigate whether endothelium-dependent vasodilation in the resistance vessels in the hindlimb is decreased in chronic
heart failure, and if so, to determine if
endothelium-derived relaxing factor (EDRF) is involved in the mechanism. We induced
heart failure in dogs by continuous rapid ventricular pacing. Under
anesthesia, an internal carotid artery-femoral artery bypass system was established and perfusion pressure to the femoral artery was kept constant. Changes in hindlimb blood flow in response to various concentrations of
acetylcholine (ACh),
adenosine 5'-diphosphate disodium
salt (
ADP) and
nitroglycerin (NTG) were examined in dogs with and without
heart failure. The vasoconstrictive responses to L-
NG-monomethyl L-arginine monoacetate (
L-NMMA) were also studied. In dogs with
heart failure, vasodilatory responses to both of the
endothelium-dependent vasodilators, ACh and
ADP, were decreased, while there were no differences in the responses to the endothelium-independent
vasodilator NTG. The vasoconstrictive response to
L-NMMA was diminished in
heart failure. Thus, endothelium-dependent vasodilation in hindlimb resistance vessels is impaired in dogs with
congestive heart failure. This impairment may be related to diminished EDRF/NO production or release in these vessels.