Interaction between capsaicin and nitrate tolerance in isolated guinea-pigheart

Capsaicin-induced increases in heart rate and coronary flow were blocked by N-G-nitro-L-Arg-methyl ester (30 mM) in Langendorff-perfused guinea-pig he arts. Neither heart rate nor coronary flow changed by capsaicin in hearts f rom animals made tolerant to the hypotensive effect of 30 mu g/kg nitroglyc erin by the administration of 50 mg/kg nitroglycerin subcutaneously 4 times a day over 3 days. We conclude that the effector function of sensory nerve s may deteriorate in nitrate tolerance. (C) 1999 Elsevier Science B.V. All rights reserved.