TY - JOUR T1 - Nonpeptide endothelin receptor antagonists: IV. Identification of receptors in rabbit colonic mucosa and smooth muscle and correlation with physiological effects. JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 1204 LP - 1210 VL - 272 IS - 3 AU - P L Smith AU - C P Lee AU - M Pullen AU - E H Ohlstein AU - G Beck AU - E P Eddy AU - P Nambi Y1 - 1995/03/01 UR - http://jpet.aspetjournals.org/content/272/3/1204.abstract N2 - Endothelin (ET) has been previously demonstrated to be a potent intestinal secretory stimuli and to elicit intestinal smooth muscle contractions. In rat distal colon, the ETA receptor antagonist cyclo[D-Asp-L-Pro-D-Val-L-Leu-D-Trp] abolishes the changes in ion transport (as measured by short-circuit current) elicited by ET-1. In this study, effects of ET-1, sarafotoxin 6c and "big" ET in the absence and presence of the endothelin receptor antagonists cyclo [D-Asp-L-Pro-D-Val-L-Leu-D-Trp] and (+/-)-3-[2-(carboxymethoxy)-4-methoxyphenyl]-1-[3,4- (methylenedioxy)phenyl]-5-(prop-1-yloxy)indan-2-carboxylic acid on ion transport in rabbit distal colon were assessed through measurement of short-circuit current changes in segments of muscle-stripped mucosa in Ussing chambers. In addition, changes in smooth muscle contraction in response to acetylcholine, ET-1, ET-3 and sarafotoxin 6c in the absence and presence of (+/-)-3-[2-(carboxymethoxy)-4-methoxyphenyl]-1-[3,4- (methylenedioxy)phenyl]-5-(prop-1-yloxy)indan-2-carboxylic acid and of cyclo [D-Asp-L-Pro-D-Val-L-Leu-D-Trp] were measured in mucosa-free preparations oriented along their longitudinal axes. Receptor binding studies with mucosal or smooth muscle homogenates were conducted with [125I]ET-1, with [125I]ET-3 and with [125I]Tyr13Suc-[Glu9,Ala11,15]-endothelin-1(8-21 ) to identify the subtypes of ET receptors present in these preparations. From studies with rabbit colonic mucosa, both binding studies and measurement of short-circuit current confirm that the ETB receptor subtype is the predominant subtype and is responsible for the changes observed in ion transport.(ABSTRACT TRUNCATED AT 250 WORDS) ER -