Pre- and postjunctional effects of N-ethylmaleimide in the isolated mouse vas deferens.
The influence of N-ethylmaleimide (NEM) on contractions due to exogenously applied noradrenaline and bethanechol and on the inhibitory effects of clonidine, of the enkephalin derivative, FK 33-824, and 2-chloroadenosine (2-CLA) on field stimulation-response curves and [3H]noradrenaline [( 3H]NA) release was studied in the isolated mouse vas deferens. Exposure to NEM (60 microM: 10 min) caused a 30% reduction of the maximal contraction due to NA but nearly abolished the response to bethanechol. NEM partially reversed the depression of the pulse width-response curves by clonidine and FK 33-824 but was without effect with 2-CLA. The contractions evoked by stimulation frequencies above 20 Hz were depressed by NEM both in presence and absence of the agonists. NEM diminished the inhibition of the stimulation-evoked release of [3H]NA by the three agonists. The prejunctional effect of NEM was markedly influenced by the stimulation parameters. These findings support the suggestion that the inhibition mediated by alpha 2-adrenoceptors, mu- and P1-receptors in the mouse vas deferens is NEM-sensitive and possibly transmitted by a pertussis toxin-sensitive G-protein.
Kaschube
M
M
Department of Pharmacology, Medical University Lübeck, F.R.G.
Brasch
H
H
D015762:2-Chloroadenosine / Q000494:pharmacology; D000818:Animals; D001626:Bethanechol Compounds / Q000494:pharmacology; D002122:Calcium Chloride / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin / Q000494:pharmacology; D004146:Dioxanes / Q000494:pharmacology; D004558:Electric Stimulation; D005033:Ethylmaleimide / Q000494:pharmacology*; D019329:Idazoxan; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology; D014649:Vas Deferens / Q000187:drug effects / Q000502:physiology
D001626:Bethanechol Compounds; D004146:Dioxanes; D015762:2-Chloroadenosine; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin; D002122:Calcium Chloride; D003000:Clonidine; D005033:Ethylmaleimide; D009638:Norepinephrine; D019329:Idazoxan