Comparison of the effects of endothelin-1 and Bay k 8644 on twitch contractions of the field-stimulated rat vas deferens.
Endothelin-1 (ET-1) potentiated both the fast and the slow components of the twitches of the isolated field-stimulated rat vas deferens, whereas Bay k 8644 potentiated only the fast component. Nicardipine tended to decrease the potentiation. ET-1, but not Bay k 8644, caused membrane depolarization and resting tension elevation, which were suppressed by nicardipine. The excitatory junction potentials (EJPs) were augmented by Bay k 8644 and the effect was not changed by nicardipine. ET-1, however, apparently did not augment the EJPs, because of the accompanying depolarization. These results indicate a difference in mechanism of the potentiating effects of ET-1 and Bay k 8644.
Shoji
T
T
R&D Division, Eisai Co., Ltd., Tokyo, Japan.
Goto
K
K
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D016232:Endothelins / Q000494:pharmacology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D014649:Vas Deferens / Q000187:drug effects* / Q000502:physiology
D016232:Endothelins; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester