Nitric oxide exerts feedback inhibition on EDHF-induced coronary arteriolar dilation in vivo

Yasuhiro Nishikawa, David W. Stepp, William M. Chilian

Research output: Contribution to journalArticle

140 Scopus citations

Abstract

Nitric oxide exerts feedback inhibition on EDHF-induced coronary arteriolar dilation in vivo. Am J Physiol Heart Circ Physiol 279: H459-H465, 2000. We tested the hypothesis that nitric oxide (NO) inhibits endothelium-derived hyperpolarizing factor (EDHF)-induced vasodilation via a negative feedback pathway in the coronary microcirculation. Coronary microvascular diameters were measured using stroboscopic fluorescence microangiography. Bradykinin (BK)-induced dilation was mediated by EDHF, when NO and prostaglandin syntheses were inhibited, or by NO when EDHF and prostaglandin syntheses were blocked. Specifically, BK (20, 50, and 100 ng-kg-1-min-1 ic) caused dose-dependent vasodilation similarly before and after administration of N(G)-monomethyl-L-arginine (L-NMMA) (3 μmol/min ic for 10 min) and indomethacin (Indo, 10 mg/kg iv). The residual dilation to BK with L-NMMA and Indo was completely abolished by suffusion of miconazole or an isosmotic buffer containing high KCl (60 mM), suggesting that this arteriolar vasodilation is mediated by the cytochrome P-450 derivative EDHF. BK-induced dilation was reduced by 39% after inhibition of EDHF and prostaglandin synthesis, and dilation was further inhibited by combined blockade with L-NMMA to a 74% reduction in the response. This suggests an involvement for NO in the vasodilation. After dilation to BK was assessed with L-NMMA and Indo, sodium nitroprus-side (SNP, 1-3 μg-kg-1-min-1 ic), an exogenous NO donor, was administered in a dose to increase the diameter to the original control value. Dilation to BK was virtually abolished when administered concomitantly with SNP during L-NMMA and Indo (P < 0.01 vs. before SNP), suggesting that NO inhibits EDHF-induced dilation. SNP did not affect adenosine- or papaverine-induced arteriolar dilation in the presence of L-NMMA and Indo, demonstrating that the effect of SNP was not nonspecific. In conclusion, our data are the first in vivo evidence to suggest that NO inhibits the production and/or action of EDHF in the coronary microcirculation.

Original languageEnglish (US)
Pages (from-to)H459-H465
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume279
Issue number2 48-2
DOIs
StatePublished - 2000

Keywords

  • Coronary microcirculation
  • Endothelium-dependent dilation
  • Endothelium-derived hyperpolarizing factor

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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