Hypothermia induces supersensitivity of mouse vas deferens to adrenergic agonists: evidence for postjunctional alpha 2-adrenoceptors.

Hypothermia-induced potentiation of alpha-adrenoceptor-mediated responses of the mouse vas deferens to noradrenaline is mainly caused by inhibition of the sites of loss. However, even after blockade of the sites of loss for noradrenaline or when using methoxamine (which is not a substrate for uptake or metabolism) hypothermia still causes a significant increase in responsiveness. This remaining supersensitivity was shown to be an increased receptor affinity. Furthermore, hypothermia revealed contractile responses to low concentrations of UK 14304 (an alpha 2-agonist).