A NEW TYPE OF DRUG ENHANCEMENT: INCREASED MAXIMUM RESPONSE TO CUMULATIVE NORADRENALINE IN THE ISOLATED RAT VAS DEFERENS

Abstract

Drugs such as the tricyclic antidepressants, some antihistamines and cocaine have been claimed to potentiate the actions of noradrenaline by interfering with its uptake by the adrenergic neurone Generally, this enhancement is shown by a parallel shift to the left of the noradrenaline dose-response curve. In the present study we observed that cocaine, in concentrations which shifted the noradrenaline dose-response curve to the left, increased the maximum contractile response of the isolated rat vas deferens to cumulative doses of noradrenaline. This finding led to an investigation of the effects of other inhibitors of catecholamine uptake on maximum responses to noradrenaline.