RESUMO
We studied the effect of various detergents (Tween-20, Triton X-100, and sodium deoxycholate) on activity and magnesium-dependent properties of Na+,K+-ATPase of the crude membrane fraction of rat cerebral cortex. All studied detergents significantly increased activity of the studied enzyme in a concentration-dependent manner. Sodium deoxycholate provided significantly higher values Na+,K+-ATPase activity (by ≈50%) than Triton X-100 and Tween-20. In the presence of Triton X-100, a changed pattern of the dependence of enzyme activity on the concentration of magnesium ions in the incubation solution was noted. Separate measurement of activities of Na+,K+-ATPase isoforms made it possible to assume that changes in magnesium-dependent properties are due to the predominant effect of Triton X-100 on ouabain-sensitive α2- and α3-isoforms.
Assuntos
Córtex Cerebral/enzimologia , Detergentes/farmacologia , ATPase Trocadora de Sódio-Potássio/efeitos dos fármacos , Animais , Fracionamento Celular , Membrana Celular/química , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Córtex Cerebral/química , Córtex Cerebral/metabolismo , Isoenzimas/efeitos dos fármacos , Isoenzimas/metabolismo , Cinética , Magnésio/metabolismo , Magnésio/farmacologia , Masculino , Octoxinol/farmacologia , Ratos , Ratos Wistar , ATPase Trocadora de Sódio-Potássio/metabolismo , Extratos de Tecidos/química , Extratos de Tecidos/metabolismoRESUMO
The effects of intramuscular administration of neostigmine and physostigmine on Na+,K+-ATPase activity in various cerebral subdivisions were examined in rats. In CNS and peripheral tissues, both agents rapidly and significantly reduced activity of cholinesterases by 30-50%. The development of intoxication did not change the marker indices of stress reaction. In the cerebral cortex, physostigmine increased Na+,K+-ATPase activity, whereas neostigmine suppressed it. In addition, neostigmine decreased activity of this enzyme in the cerebellum. In contrast, both agents produced no effects on Na+,K+-ATPase activity in the striatum. The data corroborate the view on functional interaction between Na+,K+-ATPase and nicotinic cholinoreceptors in rat cerebral cortex.