AJP - Cell Physiology, Vol 256, Issue 1 C155-C159, Copyright © 1989 by American Physiological Society
Inhibitory effect of somatostatin on vagal motoneurons in the rat brain stem in vitro
J. Nabekura, Y. Mizuno and Y. Oomura
Department of Physiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Effects of somatostatin-14 (SRIF) on membrane electrical properties were
studied in rat brain stem slice preparations maintained in vitro. SRIF
hyperpolarized the resting membrane potential and decreased the input
resistance of more than two-thirds of the 85 vagal motoneurons tested in
the dorsal motor nucleus of the vagus. These effects persisted under
synaptic blockade caused by perfusion with a solution containing
tetrodotoxin or a Ca2+-free/high-Mg2+ solution and were dependent on the
extracellular SRIF concentration (5 X 10(-8) to 1 X 10(-8) M). The Hill
coefficient was estimated to be 2. The reversal potential of SRIF-induced
hyperpolarization was affected by changing external K+ concentration. The
results suggest that, in addition to its well-known peripheral action, SRIF
may inhibit secretomotor functions of visceral organs by reducing vagal
output in the central nervous system.
