RT Journal Article SR Electronic T1 EndothelinB Receptors in Rabbit Pulmonary Resistance Arteries: Effect of Left Ventricular Dysfunction JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 895 OP 903 VO 284 IS 3 A1 Cheryl C. Docherty A1 Margaret R. Maclean YR 1998 UL http://jpet.aspetjournals.org/content/284/3/895.abstract AB The endothelin (ET) receptor that mediates vasoconstriction of the isolated rabbit pulmonary resistance artery was characterized using selective ET receptor agonists and antagonists. We also examined changes in ET-induced vasoconstriction brought about by left ventricular dysfunction using the rabbit coronary ligation model. The rank order of potency for contraction was sarafotoxin S6c (S6c) > ET-1 = ET-3, which is characteristic of an ETB-like receptor. The combined ETA/ETB receptor antagonist SB209670 (1 μM) antagonized responses to ET-1 and S6c with estimated pKb values of 6.8 ± 0.2 and 7.8 ± 0.2, respectively. BQ788 (1 μM) antagonized responses to S6c and ET-3 (but not ET-1) with estimated pKb values of 7.1 ± 0.2 and 6.6 ± 0.1, respectively. The ETA receptor antagonist FR139317 (1 μM), either alone or in combination with BQ788, did not inhibit responses to ET-1. The profile of the ET-1 response was not altered by left ventricular dysfunction. In control rabbits, the inhibitor of nitric oxide synthaseNω-nitro-L-arginine methyl ester (100 μM) had no significant effect on the potency of either ET-1 or S6c. In the coronary-ligated rabbits, however, it significantly increased the potency (10–15-fold) of both ET-1 and S6c. These results suggest that the ET receptor that mediates contraction in rabbit pulmonary resistance arteries has the characteristics of an ETB-like receptor. The responses to ET-1 are not altered by LVD but may be modified by increased release of nitric oxide. The American Society for Pharmacology and Experimental Therapeutics