Calcitonin gene-related peptide selectively relaxes contractile responses to endothelin-1 in rat mesenteric resistance arteries

J Pharmacol Exp Ther. 2009 Oct;331(1):87-95. doi: 10.1124/jpet.109.155143. Epub 2009 Jul 23.

Abstract

We tested the hypothesis that endothelin-1 (ET-1) modulates sensory-motor nervous arterial relaxation by prejunctional and postjunctional mechanisms. Isolated rat mesenteric resistance arteries were investigated with immunohistochemistry, wire-myography, and pharmacological tools. ET(A)- and ET(B)-receptors could be visualized on the endothelium and smooth muscle and on periarterial fibers containing calcitonin gene-related peptide (CGRP). Arterial contractile responses to ET-1 (0.25-16 nM) were not modified by blockade of ET(B)-receptors, NO-synthase, and cyclooxygenase or desensitization of transient receptor potential cation channel, subfamily V, member 1 (TRPV1) with capsaicin. ET-1 reversed relaxing responses to CGRP in depolarized arteries. This effect was inhibited by ET(A)-antagonists. It was not selective because ET-1 also reversed relaxing responses to Na-nitroprusside (SNP) and because phenylephrine (PHE; 0.25-16 microM) similarly reversed relaxing responses to CGRP or SNP. Conversely, contractile responses to ET-1 were, compared with PHE, hypersensitive to the relaxing effects of the TRPV1-agonist capsaicin and to exogenous CGRP, but not to acetylcholine, forskolin, pinacidil, or SNP. In conclusion, ET-1 does not stimulate sensory-motor nervous arterial relaxation, but ET(A)-mediated arterial contractions are selectively sensitive to relaxation by the sensory neurotransmitter CGRP. This does not involve NO, cAMP, or ATP-sensitive K(+) channels.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcitonin Gene-Related Peptide / physiology*
  • Endothelin A Receptor Antagonists
  • Endothelin B Receptor Antagonists
  • Endothelin-1 / antagonists & inhibitors
  • Endothelin-1 / physiology*
  • Male
  • Mesenteric Arteries / physiology*
  • Muscle Contraction / physiology*
  • Muscle Relaxation / physiology*
  • Muscle, Smooth, Vascular / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Endothelin A / physiology
  • Receptor, Endothelin B / physiology
  • Vascular Resistance / physiology*
  • Vasoconstriction / physiology
  • Vasodilation / physiology*

Substances

  • Endothelin A Receptor Antagonists
  • Endothelin B Receptor Antagonists
  • Endothelin-1
  • Receptor, Endothelin A
  • Receptor, Endothelin B
  • Calcitonin Gene-Related Peptide