Excitatory effects of cholecystokinin octapeptide on rat nodose ganglion cells in vitro.

Cholecystokinin octapeptide (CCK-8) applied by pressure evoked in the majority of rat nodose ganglion cells a rapid depolarization associated with a fall of membrane resistance and in a few cells a slow depolarization accompanied by an increase of membrane resistance. The fast depolarizations were increased and decreased by membrane hyperpolarization and depolarization; the extrapolated reversal potential was about -10 mV. The response was depressed in a Na-free solution and by d-tubocurarine (10-100 microM) but not in a Cl-deficient solution. It is concluded that CCK-8 depolarized the nodose ganglion cells by increasing cation conductances and in a few cells it also produced a slow excitation, the mechanism of which remains to be established.