Chronic cardiac denervation affects the speed of coronary vascular regulation

Objective: We tested the hypothesis that the rate of adaptation of coronary metabolic vasodilatation and autoregulation is modulated by the cardiac ne rves. Methods: Anaesthetised dogs (seven innervated (control) and seven wit h denervated hearts) were subjected to controlled pressure perfusion of the left main coronary artery, Heart rate was controlled by pacing. Results: T he steady state autoregulation curves and metabolic regulation curves were similar in the two groups. A sudden increase or decrease in heart rate was associated with a faster response (22% shorter half-times) in the innervate d than the denervated dogs (P<0.001). A sudden increase or decrease in coro nary arterial perfusion pressure was associated with a slower response (24% longer half-times) in the innervated than the denervated hearts (P<0.005). Conclusions: We conclude that the speed of response to metabolic and perfu sion pressure changes is partly mediated by cardio-cardiac reflexes. Reflex coronary vasodilatation appears to reinforce the metabolic vasodilatation of a heart rate increase and oppose the vasoconstriction in response to inc reased perfusion pressure. (C) 1999 Elsevier Science BN. All rights reserve d.