Neuron generator potentials evoked by intracellular injection of cyclic nucleotides and mechanical distension.

Depolarization of neuron membrane was shown to occur during cAMP injection by means of both iontophoresis and pressure. Distension of the neuron by means of blowing with large volumes of solution without cAMP can produce reversible responses. The time course can be made similar to that of the cAMP effect and the responses can be repeated many times in the same neuron. The effect of cAMP can be differentiated from the mechanical response by injecting small volumes of concentrated solutions. The delay in this depolarization response to cAMP is only 0.1-0.3 s. The calculated time of diffusion from the electrode tip to the membrane is about 10 times greater. The similarity of cAMP and mechanical responses and the short delay of the cAMP effect suggests that a cAMP effect may be mediated by mechanical signals in the cytoskeleton.