[Frequency potentiation mechanisms of cyclic AMP-dependent responses of snail neurons]

Intracellular injection of cAMP with the help of microiontophoresis (5-40 nA, 1-10 s) into land snail neurons induces rapid membrane depolarization. Action potentials have not influence on the following cAMP-responses. When the intervals between cAMP-injections are less than 5 minutes the effect of frequency potentiation of cAMP-responses is obtained. The experiments with cAMP-injection from two different barrels of multibarreled microelectrode show that a change of the microelectrode barrels during repetitive injections causes an abolition of the frequency potentiation effect of cAMP-responses. The results suggest that the frequency potentiation effect of cAMP-responses may be explained by peculiarities of microiontophoresis.