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Title: Pertussis toxin-insensitive G protein mediates substance P-induced inhibition of potassium channels in brain neurons. Author: Nakajima Y, Nakajima S, Inoue M. Journal: Proc Natl Acad Sci U S A; 1988 May; 85(10):3643-7. PubMed ID: 2453066. Abstract: Substance P excites neurons by suppressing inward rectification channels. We have investigated whether the substance P receptor interacts with the inward rectification channels through a guanine nucleotide-binding protein (G protein) by using dissociated cultured neurons from the nucleus basalis of newborn rats. During intracellular application of guanosine 5'-[gamma-thio]triphosphate and 5'-guanylyl imidodiphosphate, hydrolysis-resistant GTP analogues that irreversibly stimulate G proteins, substance P application almost irreversibly suppressed the inward rectification channels. Pretreatment with pertussis toxin did not significantly influence substance P action. Intracellular application of cAMP and 3-isobutyl-1-methylxanthine or of 9-(tetrahydro-2-furyl)adenine (SQ 22,536), an inhibitor of adenylate cyclase, did not alter the substance P-induced response. We conclude that the inhibition of inward rectification channels by substance P is mediated through a G protein. However, the effect is not mediated through adenylate cyclase or the cAMP system. This G protein, which is insensitive to pertussis toxin, could be an unidentified G protein.[Abstract] [Full Text] [Related] [New Search]