Role of bicarbonate ion in the postjunctional action of cocaine in the smooth muscle of the rat vas deferens.
In the HEPES-buffered physiological solution containing 20 mM bicarbonate ion, cocaine not only increased the sensitivity to norepinephrine but enhanced the maximal contractions to norepinephrine and methacholine in the rat vas deferens. Cocaine also potentiated the high potassium-induced contractions. In the solution without bicarbonate ion, such effects of cocaine were lost except for the sensitivity increase to norepinephrine. These results suggest that bicarbonate ion is crucial for the postjunctional stimulatory action of cocaine in the rat vas deferens.
Suzuki
N
N
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
Gomi
Y
Y
D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology*; D003042:Cocaine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008688:Methacholine Compounds / Q000494:pharmacology; D009130:Muscle, Smooth / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014649:Vas Deferens / Q000187:drug effects
D001639:Bicarbonates; D008688:Methacholine Compounds; D003042:Cocaine; D011188:Potassium; D009638:Norepinephrine