Soman reversibly decreases the duration of Ca2+ and Ba2+ action potentials in bullfrog sympathetic neurons.
Soman, (pinacoloxymethyl-phosphoryl fluoride) (0.1-10 microM) an irreversible cholinesterase inhibitor, reversibly reduced the duration of calcium (Ca2+)- and barium (Ba2+) spikes without significantly affecting spike amplitude in sympathetic postganglionic neurons of the adult bullfrog (Rana catesbeiana). The soman-induced shortening of the spike duration was not prevented by pretreatment with either (+)-tubocurarine (100 microM) or hexamethonium (100 microM) and atropine (10 microM) and was also recorded from acutely-dissociated sympathetic neurons. These results suggest that soman has a direct action to decrease calcium entry through voltage-dependent channels activated during a spike. This effect may contribute to both the decrease in the duration of the spike after-hyperpolarization (AHP) and the enhanced neuronal excitability produced by soman in these neurons.
Heppner
T J
TJ
Department of Anatomy and Neurobiology, University of Vermont, College of Medicine, Burlington 05405.
Fiekers
J F
JF
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001464:Barium / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects; D066298:In Vitro Techniques; D009474:Neurons / Q000187:drug effects*; D011892:Rana catesbeiana; D012999:Soman / Q000494:pharmacology*; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects*
D015220:Calcium Channels; D001464:Barium; D012999:Soman; D002118:Calcium