Evidence for a cyclic GMP mechanism in the mediation of hippocampal post-tetanic potentiation.
Correlative electrophysiological and biochemical techniques were used to study hippocampal post-tetanic potentiation in acutely prepared rabbits following stimulation of the medial septal region and contralateral hippocampal field CA3. The results indicate that calcium ions, guanosine-3':5'-monophosphate, and phosphodiesterase inhibitors selectively enhanced the duration of post-tetanic potentiation. Potassium ions selectively enhanced tetanic potentiation. Adenosine-3':5'-cyclic monophosphate suppressed both tetanic and post-tetanic potentiation. The electrophysiological findings were supported by biochemical observations that guanosine-3':5'-monophosphate levels show marked increases following tetanic stimulation of either the medial septal region or contralateral hippocampal field CA3 pathways. The data suggest that a calcium-dependent process in the presence of a guanosine-3':5'-monophosphate mechanism promotes periods of hippocampal pyramidal cell hyperexcitability. The mechanism by which the cyclic nucleotide alters potentiation does not appear to be coupled to a single receptor variety.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology / Q000502:physiology*; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D010208:Papaverine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D009435:Synaptic Transmission / Q000187:drug effects
D010208:Papaverine; D000242:Cyclic AMP; D006152:Cyclic GMP; D011188:Potassium; D002118:Calcium