Abstract
Coronary blood flow regulation was studied in dogs with an intact or chronically decentralized
intrinsic cardiac nervous system. We also examined the effect of angiotensin-converting
enzyme inhibition (ACEI) on coronary autoregulatory pressure–flow relations and distribution
of blood flow since the renin–angiotensin system may play a critical role in vasoregulation.
Myocardial oxygen demand was reduced in the chronic decentralized dogs compared to
the control dogs. The lower pressure limit of the autoregulatory pressure–flow relation
was similar for the control and chronic decentralized dogs (47±2 and 44±7 mm Hg, respectively;
p=NS). After ACEI, the lower pressure limit shifted leftward to 40 mm Hg (p=0.001) in both groups. Concomitant blockade of cyclooxygenase, bradykinin catabolism
and nitric oxide synthase had no further effect on the lower pressure limit. Total
myocardial blood flow was lower (p=0.001) in the chronic decentralized dogs compared to the control dogs, while transmural
distribution of blood flow was preserved in both groups. The results show that even
though myocardial oxygen requirements are lower in the chronically decentralized heart
compared to controls, coronary autoregulation is maintained at levels observed in
normally innervated hearts. The present findings indicate that intrinsic cardiac neurons
contribute to coronary autoregulatory control and myocardial blood flow distribution
even in the absence of cardiac connections to the central nervous system. In addition,
in the chronic decentralized dog, ACEI allows the heart to work at lower coronary
perfusion pressures while myocardial blood flow distribution is preserved.
Keywords
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Article info
Publication history
Accepted:
December 14,
2001
Received in revised form:
November 29,
2001
Received:
October 26,
2001
Identification
Copyright
© 2002 Elsevier Science B.V. Published by Elsevier Inc. All rights reserved.
