Comparative analysis of the action of a vasopressin analogue on functionally different neurons of the edible snail.

Application of desglycine-argininvasopressin (DG-AVP) had a differing effect on different types of cell isolated from the central nervous system of the edible snail. We observed in the neurosecretory cells an increase in the frequency of spontaneous impulse activity and, as a rule, the appearance of bursts of impulses, most frequently of synaptic origin with the exception of PPal neurons and one of the neurosecretory cells of the left parietal ganglion. The intensity of the burst activity of these cells was due to an increase in the amplitude of the waves of the membrane potential. The activation of the neurosecretory cell system brought about an increase in the frequency and amplitude of the EPSPs in secondary-sensory neurons, this leading to an increased probability of the appearance of action potentials in them. On prolonged action the spontaneous EPSPs in these cells began to be arranged in bursts. The excitability and membrane resistance of these cells remained constant. The DG-AVP had no effect on the primary-sensory neurons and motoneurons.