[Possible concentration-dependent mechanism of action exerted by epinephrine on giant neurons]

The results of an investigation carried out suggest that both the stimulating and inhibitory action of epinephrine on the neuronal activity are mediated by the adenylate-cyclase system. The reason of the effect of epinephrine depending on its concentration is, apparantly, the polyfunctionality of the "second mediator"--cAMP and the primordial existence in the cells of processes oppositely influencing its functional activity, whose intensity depends on the concentration of cAMP.