Effect of SR59230A on atypical beta-adrenoceptor mediating relaxation in the Guinea Pig gastric fundus.
The purpose of the present study was to clarify whether atypical beta-adrenoceptors which presented in the guinea pig gastric fundus are beta(3)-adrenoceptors or putative beta(4)-adrenoceptors. In the presence of both the selective beta(1)-adrenoceptor antagonist atenolol (10(-4) mol/l) and the selective beta(2)-adrenoceptor antagonist butoxamine (10(-4) mol/l), the selective beta(3)-adrenoceptor antagonist SR59230A caused a concentration-dependent rightward shift of the concentration-response curve to catecholamines (isoprenaline, noradrenaline and adrenaline) and beta(3)-adrenoceptor agonists (BRL37344 and CGP12177A) in the guinea pig gastric fundus. Schild plot analyses of SR59230A against these agonists gave pA(2) values of 7.35 +/- 0.03 (isoprenaline), 7.26 +/- 0.04 (noradrenaline), 7.26 +/- 0.05 (adrenaline), 7.79 +/- 0.03 (BRL37344) and 6.74 +/- 0.03 (CGP12177A), respectively, and all Schild slopes were not significantly different from unity. These results suggest that atypical beta-adrenoceptors mediating relaxant responses of these agonists in the guinea pig gastric fundus are beta(3)-adrenoceptors rather than putative beta(4)-adrenoceptors.
Horinouchi
T
T
Department of Chemical Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
Yamamoto
Y
Y
Koike
K
K
D058673:Adrenergic beta-3 Receptor Antagonists; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005748:Gastric Fundus / Q000187:drug effects* / Q000502:physiology; D006168:Guinea Pigs; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects* / Q000502:physiology; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D011412:Propanolamines / Q000494:pharmacology*; D022702:Receptors, Adrenergic, beta-3 / Q000502:physiology
C097869:3-(2-ethylphenoxy)-1-(1,2,3,4-tetrahydronaphth-1-ylamino)-2-propanol oxalate; D058673:Adrenergic beta-3 Receptor Antagonists; D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D022702:Receptors, Adrenergic, beta-3