Role of cyclase system in generation of pacemaker activity in fast and slow bursters in snail, Helix pomatia

Abstract

1. The effect of external application of theophylline, an inhibitor of cyclic nucleotide phosphodiesterases, and intracellular injection of H-8, an inhibitor of protein kinase A, on pacemaker activity in both identified fast RPal and slow RPa2 bursting neurons of snail Helix pomatia has been investigated. 2. The RPa2 (right parietal 2) neuron possessing slow bursting pacemaker activity with a period of membrane potential oscillation of about 100 sec was identified in right parietal ganglion of Helix pomatia. 3. External application of theophylline produced an increase of bursting activity in RPal fast burster and transformed beating activity into the slow bursting one or increased slow bursting activity in RPa2 neuron. 4. Intracellular injection of H-8 produced a slowly developing long-lasting inhibition of pacemaker activity in both fast RPal and slow RPa2 bursters. The participation of adenylate cyclase system in generation of pacemaker activity in identified neurons of the snail is discussed.