Enhancement of beta-adrenergic responses by Gi-linked receptors in rat hippocampus.
Many excitable cells express a class of neurotransmitter receptors functionally defined by their ability to increase potassium conductance through G proteins of the Gi/G(o) class that directly activate the potassium channels. Biochemical studies have shown that these same receptors can also inhibit forskolin-stimulated adenylyl cyclase, although the functional significance of this effect remains unclear. In this study electrophysiological techniques were used to examine how activation of serotonin and gamma-aminobutyric acid receptors belonging to this class affect beta-adrenergic responses signaled through adenylyl cyclase. Surprisingly, activation of these receptors not only failed to inhibit but actually enhanced beta-adrenergic responses. These observations are consistent with evidence indicating that Gi-linked receptors can enhance the ability of Gs to stimulate certain adenylyl cyclases.
Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, Missouri 63104.
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D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D004553:Electric Conductivity; D004594:Electrophysiology; D019204:GTP-Binding Proteins / Q000502:physiology*; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D011963:Receptors, GABA-A / Q000502:physiology; D011985:Receptors, Serotonin / Q000502:physiology
D015221:Potassium Channels; D011943:Receptors, Adrenergic, beta; D011963:Receptors, GABA-A; D011985:Receptors, Serotonin; D005576:Colforsin; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D001418:Baclofen; D009638:Norepinephrine