Calcitonin Gene-Related Peptide Selectively Relaxes Contractile Responses to Endothelin-1 in Rat Mesenteric Resistance Arteries □ S Merlijn J. P. M. T. Meens, Gregorio E. Fazzi, Marc A. van Zandvoort, and Jo G. R. De Mey Departments of Pharmacology and Toxicology (M.J.P.M.T.M., G.E.F., J.G.R.D.M.) and Biomedical Technology (M.A.v.Z.), Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands Received April 15, 2009; accepted July 21, 2009 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 -recep- tors 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 M) similarly reversed relaxing responses to CGRP or SNP. Conversely, contractile responses to ET-1 were, compared with PHE, hypersensitive to the relax- ing 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 neurotransmit- ter CGRP. This does not involve NO, cAMP, or ATP-sensitive K + channels. The bicyclic 21-amino-acid peptide endothelin-1 (ET-1) is involved in pulmonary hypertension, heart failure, and can- cer (Bagnato and Rosano `, 2008; Kirkby et al., 2008; Opitz et al., 2008). It binds with comparable high affinity to two distinct receptor subtypes, ET A and ET B , belonging to the G-protein-coupled receptor superfamiliy (Davenport, 2002; Masaki, 2004). In the vasculature, the detrimental effects of ET-1, (i) long-lasting vasoconstriction (Kawamata et al.), (ii) cell growth, proliferation, and migration, (iii) production of reactive oxygen species, and (iv) inflammation, are mediated by ET A -receptors on vascular smooth muscle cells (VSMCs) (Masaki, 2004; Hynynen and Khalil, 2006; Schneider et al., 2007). Counterbalancing beneficial effects such as nitric ox- ide (NO) synthesis, vasodilatation, and scavenging of circu- lating ET-1 are mediated by endothelial ET B -receptors (Na- kashima and Vanhoutte, 1993; Woods et al., 1999; Johnstro ¨m et al., 2005; Schneider et al., 2007). Yet, therapeutic effects in experimental animal models and patients do not differ pro- foundly between selective ET A -antagonists and mixed ET A / ET B -antagonists (Masaki, 2004; Battistini et al., 2006; Dhaun et al., 2007; Schneider et al., 2007; Opitz et al., 2008). This may be due to effects of ET-1 on other cell types. ET A -receptors are not only expressed by VSMC but also by periarterial sensory-motor nerves (Wang and Wang, 2004; Plant et al., 2006). These nerves mediate nonadrenergic non- cholinergic vasodilatation involving the neurotransmitter calcitonin gene-related peptide (CGRP) that can activate ad- This study was performed within the framework of Top Institute Pharma Project T2–108-1: Metalloproteases and Novel Targets in Endothelial Dysfunc- tion. Article, publication date, and citation information can be found at http://jpet.aspetjournals.org. doi:10.1124/jpet.109.155143. □ S The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material. ABBREVIATIONS: ET-1, endothelin-1; BIBN4096BS, 1-piperidinecarboxamide, N-[2-[[5-amino-1-[[4-(4-pyridinyl)-1-piperazinyl]carbonyl]pen- tyl]amino]-1-[(3,5-dibromo-4-hydroxyphenyl)methyl]-2-oxoethyl]-4-(1,4-dihydro-2-oxo-3(2H)-quinazolinyl); bosentan, 4-tert-butyl-N-[6-(2-hy- droxyethoxy)-5-(2-methoxyphenoxy)-2-(pyrimidin-2-yl)pyrimidin-4-yl]benzene-1-sulfonamide; BQ123, cyclo (D-Trp-D-Asp-Pro-D-Val-Leu); BQ788, N-cis-2,6-dimethyl-piperidinocarbonyl-L--methylleucyl1-D-1methoxycarbonyl-tryptophanyl-D-norleucine; L-NAME, N  -nitro-L-arginine methyl ester; TRPV1, transient receptor potential cation channel, subfamily V, member 1; VSMC, vascular smooth muscle cell; CGRP, calcitonin gene-related peptide; AC, adenylate cyclase; CAPS, capsaicin; KRB, Krebs-Ringer bicarbonate-buffered physiological salt solution; INDO, indomethacin; ACh, acetylcholine; PHE, phenylephrine. 0022-3565/09/3311-87–95$20.00 THE JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS Vol. 331, No. 1 Copyright © 2009 by The American Society for Pharmacology and Experimental Therapeutics 155143/3517524 JPET 331:87–95, 2009 Printed in U.S.A. 87 http://jpet.aspetjournals.org/content/suppl/2009/07/23/jpet.109.155143.DC1 Supplemental material to this article can be found at: at ASPET Journals on July 20, 2018 jpet.aspetjournals.org Downloaded from