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The Pharmacology of the GABA-induced biphasic response in guinea-pig celiac ganglion neurons in vitro

Lu Fangmin, Xing Baoren, Chen Yizhang

Department of Physiology, Second Military Medical University. Shanghai

Abstract

In guinea-pig celiac ganglion neurons, GABA induced a biphasic response, i.e. a depolarizing response associated with a resistance decrease followed by a hyperpolarizing response associated with a resistance increase. Such response persisted in low Ca~(2+) high Mg~(2+) medium. The GABA-induced biphasic response was mimicked by muscimol and inhibited by bicuculline methiodide (100#mu#mol/L)and picrotoxin(100—300#mu#mol/L). At doses producing almost equal depolarizing responses, muscimol was weaker in producing hyperpolarizing responsis than GABA. Baclofen had no effect on membrane potentials of the ganglion cells. These results suggest that hte depolarizing phase of the GABA-induced biphasic response is mediated by GABA_(A)/Cl~(-) ionophore receptor complex and the hyperpolarzing phase may be mediated by a novel type of GABA receptor possessing similar pharmacological properties as the classified GABA receptor.

Key words: GABA;Biphasic response;Membrane resistallce;GABA-benzodiatepine receptors; Sympathetic ganglia

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Citing This Article：

Lu Fangmin, Xing Baoren, Chen Yizhang. The Pharmacology of the GABA-induced biphasic response in guinea-pig celiac ganglion neurons in vitro. Acta Physiol Sin 1994; 46 (3): (in Chinese with English abstract).