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Chronic cardiac denervation affects the speed of coronary vascular regulation
I Vergroesen1, D Merkus, J W van Teeffelen
1Department of Medical Physics, Academic Medical Centre, University of Amsterdam, The Netherlands. I.Vergroesen@amc.uva.nl
Objective:
We tested the hypothesis that the rate of adaptation of coronary metabolic vasodilatation and autoregulation is modulated by the cardiac nerves.
Methods:
Anaesthetised dogs (seven innervated (control) and seven with denervated hearts) were subjected to controlled pressure perfusion of the left main coronary artery. Heart rate was controlled by pacing.
Results:
The 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 innervated than the denervated dogs (P < 0.001). A sudden increase or decrease in coronary 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 perfusion 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 increased perfusion pressure.