EFFECTS OF LITHIUM ON GANGLIONIC HYPERPOLARIZATION AND BLOCKADE BY DIMETHYLPHENYLPIPERAZINIUM

¹ Department of Pharmacology, University of Connecticut, Schools of Medicine and Dental Medicine, Hartford, Connecticut

Ganglionic responses to dimethylphenylpiperazinium (DMPP) were modified in the following ways by ouabain (100 µg i.a.). The period of depolarization and associated early blockade of transmission were enhanced. The late occurring hyperpolanization was diminished, and the late occurring blockade of transmission was unaffected. Ganglionic depolarization and blockade by lobeline were intensified by ouabain. Perfusion of the ganglia with media containing lithium ions resulted in the abolition of DMPP-induced hyperpolarization but had no effect on the late occurring blockade of transmission. Conversely, perfusion of the ganglia with media at low temperature (22-25°C) had no effect on hyperpolarization by DMPP but prevented the appearance of the late occurring blockade. Collectively, the results indicate that the DMPP-induced hyperpolarization and late occurring blockade were temporally but not causally related events.