Bojorge G, de Lores Arnaiz G R
Instituto de Biologia Celular, Facultad de Medicina, UBA, Paraguay 2155, (1121) Buenos Aires, Argentina; Argentina and Cätedra de Farmacologia, Facultad de Farmacia y Bioquimica, UBA, Junin 956, (1113) Buenos Aires, Argentina.
Neurochem Int. 1987;11(1):11-6. doi: 10.1016/0197-0186(87)90142-2.
The effect of insulin in vitro on ATPase activities of nerve ending membranes and whole homogenates of rat cerebral cortex was studied. Membranes Na(+), K(+)-ATPase activity was not modified by 6.1 or 7.6 mU/ml insulin and it was inhibited 24-40% by 12.2-205 mU/ml insulin. Membranes Mg(2+)-ATPase activity was not modified by any of these insulin concentrations. In order to observe Na(+), K(+)-ATPase inhibition, prior to the enzyme assay, a preincubation period of the enzyme with insulin was required. The effect of insulin was dependent on the length of the enzyme incubation period. When the incubation period lasted 10 or 15 min no changes in ATPase activities were found; when the incubation period lasted 30 and 60 min, total and Na(+), K(+)-ATPase activities were inhibited 35-50%; Mg(2+)-ATPase activity appeared inhibited only after a 60 min incubation period. The addition of 205 mU/ml insulin inhibited by 40% Na(+), K(+)-ATPase activity of water whole homogenates but stimulated the enzyme up to 40% in sucrose whole homogenates. Both effects were observed in recently prepared cerebral cortex homogenates but not if the homogenates had been standing in the cold for 60 min before the enzyme assay. It is suggested that the insulin effect-stimulatory or inhibitory-is dependent on the integrity of some membranes of the cell.
研究了胰岛素在体外对大鼠大脑皮层神经末梢膜及全匀浆ATP酶活性的影响。6.1或7.6 mU/ml胰岛素对膜Na(+)、K(+)-ATP酶活性无影响，而12.2 - 205 mU/ml胰岛素可使其活性抑制24 - 40%。这些胰岛素浓度对膜Mg(2+)-ATP酶活性均无影响。为观察Na(+)、K(+)-ATP酶的抑制作用，在酶测定前，酶需与胰岛素预孵育一段时间。胰岛素的作用取决于酶孵育时间的长短。当孵育时间为10或15分钟时，ATP酶活性未发现变化；当孵育时间为30和60分钟时，总ATP酶及Na(+)、K(+)-ATP酶活性被抑制35 - 50%；Mg(2+)-ATP酶活性仅在孵育60分钟后出现抑制。加入205 mU/ml胰岛素可使水全匀浆的Na(+)、K(+)-ATP酶活性抑制40%，但使蔗糖全匀浆中的该酶活性增强40%。这两种效应在新制备的大脑皮层匀浆中均能观察到，但如果匀浆在酶测定前在低温下放置60分钟则不会出现。提示胰岛素的刺激或抑制作用取决于细胞某些膜的完整性。
