Effects of Ijingtang fractions on activities of NaK ATPase and Ca ATPase in rat brain synaptosome

이진탕 분획엑스가 synaptosomal NaK ATPase와 Ca ATPase의 활성도에 미치는 영향

To explore the action mechanism of Ijintang in the brain, the authors investigated the effects of Ijintang fractions on MgNaK ATPase and MgCa ATPase in rat brain synaptosomes prepared from cerebral cortex. The activities of MgNaK ATPase and MgCa ATPase were assayed by the level of inorganic phosphate liberated from the hydrolysis of ATP. Fraction WH-95-7 at the concentration of $10^{-2}%$ decreased the activity of MgNaK ATPase about 34.1% and also reduced the activity of MgCa ATPase about 49.3% But, other fractions (WB-95-7, WC-95-7, MB-95-7, MC-95-7, MH-95-7) did not significantly changed the activities of the MgNaK ATPase and MgCa ATPase The decreased activity of MgNaK ATPase by WH-95-7 will decrease the rate of $Ca^{2+}$ efflux, probably via an Na-Ca exchange mechanism and will increase the rate of $Ca^{2+}$ entry by the depolarization of nerve terminals. The reduced activity of MgCa ATPase by WH-95-7 will result in the decreased efflux of $Ca^{2+}$. As a conclusion, it can be speculated that lithium elevates the intrasynaptosomal $Ca^{2+}$ concentration via inhibition of the activities of MgNaK ATPase and MgCa ATPase. and this increased $[Ca^{2+}]i$ will cause the release of neurotransmitters.