Propranolol blocks cocaine-induced potentiation of the contraction in the smooth muscle of the rat vas deferens.
In the smooth muscle of the rat vas deferens, 10(-5) M cocaine shifted the dose-response curve to norepinephrine to the left and enhanced the maximal contractions to norepinephrine and methacholine. Propranolol at 10(-4) M almost completely blocked these potentiating effects of cocaine. Sotalol or lidocaine at 10(-4) M did not block the potentiating action of cocaine. The cocaine-induced enhancement of the methacholine contraction and its blockade by propranolol was observed in the dibenamine-treated vas deferens. Propranolol also blocked the depolarization-induced enhancement of the methacholine contraction. Together with the previous study demonstrating the calcium-antagonist action for propranolol, these results suggest that propranolol blocks the cocaine-induced enhancement by inhibiting the calcium influx through the potential-dependent calcium channel in the rat vas deferens.
Suzuki
N
N
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
Gomi
Y
Y
Inagaki
O
O
Ono
K
K
Kasuya
Y
Y
D000818:Animals; D003042:Cocaine / Q000037:antagonists & inhibitors*; D066298:In Vitro Techniques; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013015:Sotalol / Q000494:pharmacology; D014649:Vas Deferens / Q000187:drug effects
D008012:Lidocaine; D011433:Propranolol; D013015:Sotalol; D003042:Cocaine