Insulin stimulates the activity of membrane-bound ATPase isolated from frog skeletal muscle and from rat brain. The increase in activity of the membrane-bound ATPase system isolated from frog ranged from 9-8 to 53% at concentrations of Na+ (25 mM), K+ (10 mM), and ATP (2 mM) similar to those in in vivo experiments conducted previously (Moore, 1973). The increased activity of the membrane-bound ATPase is, therefore, at least as great as the insulin-induced increase in Na efflux (10-38%) from intact cells (Moore, 1973). If the concentration of Na+ is lowered to 4 mM and that of ATP lowered to 0-5 mM albumin, and 10(6) M, the increase in ouabain-inhibitable ATPase activity can reach as high as 400%. 2. Ouabain, at a concentration (10(-3) M) sufficient to inhibit stimulation of the frog ATPase by increasing Na from 4 to 25 mM, completely blocked the stimulation of ATPase activity due to insulin. 3. At 2 mM-ATP, 100 mM-Na+, and 20 mM-K+, conditions which maximally activate the (Na+ + K+)-ATPase, insulin did not increase the ATPase, activity. Stimulation was consistently seen at 10 mM-K+, 0-5 mM-ATP, and either 4 mM or 25 mM-Na+. 4. The finding that insulin does not stimulate the ATPase activity in conditions in which the (Na+ + K+)-ATPase component is maximally activated and especially the fact that ouabain can reproducibly inhibit insulin stimulation of the membrane-bound ATPase activity strongly suggest that interaction of insulin with its receptor upon the plasma membrane somehow stimulates the (Na+ + K+)-ATPase system (ouabain sensitive; ATP phosphohydrolase, EC (3.6.1.3). These results are consistent with previous studies of the effect of insulin upon Na efflux from intact cells (Moore, 1973) and support the previous conclusion that the component of Na efflux stimulated by insulin is active. The evidence suggests that insulin probably does not affect Vmax of the (Na+ + K+)-ATPase system, but may increase the affinity of the enzyme system to one or more effectors, most likely Na+, ATP, and perhaps K+. 5. Oxidized glutathione (2-7 X 10(-6) M), 10(-6) M, 10(-7) M, and 10(-8) M cyclic AMP did not affect the ATPase activity 10(-6)Malbumin, and . 6. The results are consistent with the view that the Na pump, (Na+ + K+)-ATPase, is intimately involved with the physiological action of insulin and may be transducer between the binding of insulin to its receptor on the plasma membrane and the cellular actions of insulin.
摘要
胰岛素可刺激从青蛙骨骼肌和大鼠大脑中分离出的膜结合ATP酶的活性。在与先前体内实验（Moore，1973）相似的Na⁺（25 mM）、K⁺（10 mM）和ATP（2 mM）浓度下，从青蛙分离出的膜结合ATP酶系统活性增加幅度在9%至53%之间。因此，膜结合ATP酶活性的增加至少与胰岛素诱导的完整细胞中Na⁺外流增加（10%至38%）一样大（Moore，1973）。如果将Na⁺浓度降至4 mM，ATP浓度降至0.5 mM，加入白蛋白和10⁻⁶ M，哇巴因抑制的ATP酶活性增加可高达400%。2. 哇巴因浓度为10⁻³ M时，足以通过将Na⁺从4 mM增加到25 mM来抑制青蛙ATP酶的刺激作用，它完全阻断了胰岛素对ATP酶活性的刺激。3. 在2 mM - ATP、100 mM - Na⁺和20 mM - K⁺（这些条件可最大程度激活（Na⁺ + K⁺）-ATP酶）下，胰岛素并未增加ATP酶活性。在10 mM - K⁺、0.5 mM - ATP以及4 mM或25 mM - Na⁺时，始终能观察到刺激作用。4. 在（Na⁺ + K⁺）-ATP酶成分被最大程度激活的条件下，胰岛素不刺激ATP酶活性，尤其是哇巴因能够反复抑制胰岛素对膜结合ATP酶活性的刺激这一事实，强烈表明胰岛素与其在质膜上的受体相互作用以某种方式刺激了（Na⁺ + K⁺）-ATP酶系统（对哇巴因敏感；ATP磷酸水解酶，EC（3.6.1.3）。这些结果与先前关于胰岛素对完整细胞中Na⁺外流影响的研究（Moore，1973）一致，并支持先前的结论，即胰岛素刺激的Na⁺外流成分是主动的。证据表明胰岛素可能不影响（Na⁺ + K⁺）-ATP酶系统的Vmax，但可能增加该酶系统对一种或多种效应物（最有可能是Na⁺、ATP，也许还有K⁺）的亲和力。5. 氧化型谷胱甘肽（2 - 7×10⁻⁶ M）、10⁻⁶ M、10⁻⁷ M和10⁻⁸ M环磷酸腺苷不影响ATP酶活性，10⁻⁶ M白蛋白也不影响。6. 这些结果与以下观点一致，即钠泵（Na⁺ + K⁺）-ATP酶与胰岛素的生理作用密切相关，并且可能是胰岛素与其在质膜上的受体结合与胰岛素的细胞作用之间的转换器。
