Gq/11 and PLC-[beta]1 Mediate the Substance P-Induced Inhibition of an Inward Rectifier K + Channel in Brain Neurons. Takano, K., J. Yasufuku-Takano, T. Kozasa, W. D. Singer, S. Nakajima, and Y. Nakajima. Department of Anatomy and Cell Biology and  Department of Pharmacology, University of Illinois at Chicago, College of Medicine, Chicago, IL 60612; _ Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75235.
APStracts 3:0106N, 1996.
1 . Substance P (SP) induces a slow neuronal excitation in cholinergic neurons from the nucleus basalis by suppressing an inwardly rectifying K + current (K ir ). We have determined which G protein [alpha]-subuint mediates this SP effect. 2 . After intracellularly injecting antibody against each [alpha]- subunit of G proteins (G q[alpha]/11[alpha] , G 12[alpha] , and G 13[alpha] ) with an Eppendorf microinjector, we examined, by using the whole-cell patch clamp and the on-cell mode of single channel recording, the effect of SP on K ir in cultured neurons of the nucleus basalis . The effect of SP on K ir was substantially reduced in neurons injected with antibodies to G q[alpha]/11[alpha] but not with antibodies to G 12[alpha] or G 13[alpha] . 3 . The effects of antibodies against three isozymes of phospholipase C (PLC- [beta]1, PLC-[beta]2, and PLC-[beta]3) were tested. The SP-induced suppression of K ir was reduced by antibody against PLC-[beta]1 but not by antibodies against PLC-[beta]2 or PLC-[beta]3. 4 . We conclude that the SP-induced inhibition of K ir in nucleus basalis neurons is mediated by G q /11 and PLC- [beta]1.

Received 25 April 1996; accepted in final form 22 May 1996.
APS Manuscript Number J348-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 June 96