[Mechanism of the antispasmogenic action of some substances that affect the 3', 5'-AMP system]

The authors carried out studies on isolated segmets of ileum with a length of 3 sm. obtained from both male and female, mature and immature guinea pigs and adult male and female rats as well as on isolated vasa deferntia, obtained from guinea pigs and rats. They examined the influence of a group of substances, known as stimulators and inhibitors of adenyl-cyclase and phosphodiesterase (isoprenaline, lithium sulfate, imidazol, theophiline and eupaverine) on the spasmogenic effects of acethylcholine (on ileum) and of noradrenaline (on vas deferens). These substances were used in doses, which were subthreshold in respect to their effect on the biogenesis and exzymic inactivation of the cyclic AMP. The authors found certain species, adult and sex differences in the spasmogenic effects of acethylcholine and noradrenaline. The examined substances lowered the spasmogenic effects of acethylcholine and noradrenaline in most of the experiments. Since the examined substance-classical means for altering the endogenous production of the cyclic AMP-show antispasmogenic effect in concentrations subthreshold for their influence on the level of the cyclic AMP, an inference is made that their inherent antispasmogenic effect is due also to a mechanism, which does not require the inclusion of the system of the cyclic AMP.