INFLUENCE OF PERTUSSIS TOXIN ON THE CALCITONIN-OPIOID INTERACTION IN ISOLATED-TISSUES

1 In order to clarify one of the mechanisms involved in the analgesic effect of calcitonin, we have tested the in vitro modifications induce d by calcitonin on the effect of opioids. 2 The inhibition of the cont ractions induced by opioids or clonidine, in guinea-pig ileum or in mo use vas deferens, were significantly reduced in tissues incubated with pertussis toxin (PTX). When tissues were incubated with PTX and calci tonin, the inhibitory effect was restored. 3 These results suggest tha t calcitonin is able to potentiate a non-PTX-sensitive mechanism of tr ansduction and support the possibility of involvement of similar G-pro teins in the effects of opioid and alpha(2)-adrenoceptor agonists.