Influence of temperature and cocaine on responses of the isolated mouse vas deferens to adrenergic amines.
Lowering the bath temperature from 37 degrees C to 20 degrees C resulted in supersensitivity of the isolated mouse was deferens to norepinephrine. Dose-response curves to norepinephrine were shifted to the left along the log dose axis (enhanced potency) and the maximum degree of contraction that could be elicited was increased. The effect of cocaine on norepinephrine effects was qualitatively the same as hypothermia. Both treatments enhanced the potencies of other alpha receptor agonists that are substrates for the adrenergic neuronal membrane uptake mechanism. Neither treatment enhanced the potency of methoxamine, which is not taken up by adrenergic neurons, but hypothermia increased the methoxamine-induced maximum contractile height. Uptake of 14C-norepinephrine by the vas deferens was abolished by cocaine and low temperature. The data suggest that enhanced potency of adrenergic amines by hypothermia results from an inhibition of uptake by adrenergic neurons. Increased height of maximum contraction at low temperature may be partly due to decreased neuronal uptake, but other mechanisms are also likely to be involved in this effect.
D000818:Animals; D001679:Biogenic Amines / Q000494:pharmacology*; D003042:Cocaine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008729:Methoxamine / Q000494:pharmacology; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D008771:Nordefrin / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D013696:Temperature; D014649:Vas Deferens / Q000187:drug effects* / Q000378:metabolism
D001679:Biogenic Amines; D010656:Phenylephrine; D008729:Methoxamine; D003042:Cocaine; D008771:Nordefrin; D009638:Norepinephrine