Effect of somatostatin on the vagal motor neuron in the rat.

Somatostatin-14 (SOM) effects on electrical properties of membrane in rat brainstem slice preparations were studied in vitro by intracellular recording. Vagal motoneurons in the nucleus dorsalis motoris nervi vagi (DMV) were hyperpolarized by SOM. SOM increased both negativity of membrane potential and input membrane conductance, and decreased synaptic noise. The effects persisted during synaptic blockade by tetrodotoxin (TTX) or [Ca]o-free-high-[Mg]o perfusion. The reversal potential of the hyperpolarization induced by SOM depended on [K]o concentration. Hill's coefficient calculated from the dose-response curve was 2. The results suggest that SOM may inhibit visceral organ functions through the DMV.