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Effect of GABAergic Compounds on the Anion-Sensitive Mg2+-ATPase from Bream (Abramis brama L.) Brain

S. A. Menzikov* and O. V. Menzikova

Papanin Institute of Biology of Inland Waters, Russian Academy of Sciences, Borok, Yaroslavl Region, 152742 Russia; fax: (085) 225-3845; E-mail: sam@ibiw.yaroslavl.ru

* To whom correspondence should be addressed.

Received July 29, 1999; Revision received October 27, 1999
Preincubation of plasma membranes from bream brain with 10-8-10-4 M gamma-aminobutyric acid (GABA) or muscimol increased the anion-sensitive Mg2+-ATPase activity. The activating effect of neurotransmitters on the Mg2+-ATPase is enhanced with increasing preincubation time of the membranes with the ligands, decreases with increasing Mg2+-ATP concentration in the incubation medium, and is inhibited in the presence of the GABAa-receptor antagonist, bicuculline (90 µM). The anions Cl-, Br-, and I- stimulate the basal Mg2+-ATPase activity, and an effect of 10-4 M GABAin the presence of anions was not found. It is supposed that GABAergic ñhemicals modify the anion-sensitive Mg2+-ATPase in a receptor-dependent way.
KEY WORDS: fish, brain, bream, plasma membranes, Mg2+-ATPase, anions, GABA, muscimol, bicuculline