Erlij D
Pflugers Arch. 1984 Apr;400(4):413-7. doi: 10.1007/BF00587542.
We have measured the effects of concentrations of vanadate ranging between 0.01 and 10 mM on the 22Na efflux of frog sartorius muscles. The addition of vanadate had no effects when concentrations lower than 0.5 mM were used; higher concentrations increased Na efflux. The increase was abolished by the addition of ouabain (10(-5)M). In muscles pretreated with ouabain vanadate did not modify Na efflux. The stimulatory effects of vanadate on Na efflux were also observed in Na-free solutions indicating that the efflux of vanadate was not caused mainly either by an increase in the exchange of Na for Na or by an increase in Na entry into the muscle. We also examined the effects of vanadate on muscles immersed in solutions containing 20 mM K+; both vanadate and increased K+ produced stimulations of Na efflux that were additive. Similarly when the effects of vanadate and insulin were measured on the Na efflux of the same muscle, additive effects were found. As the ouabain-sensitive Na efflux in frog muscle is generally agreed to be due to the activity of the Na-K ATPase, our findings suggest that the net effect of vanadate in intact muscle cells is an increase in the activity of the Na pump. Since vanadate affects many enzymes it is quite possible that the stimulatory action is not due to a direct effect on the Na-K ATPase but may be mediated through an intermediary step.(ABSTRACT TRUNCATED AT 250 WORDS)
我们测定了浓度在0.01至10 mM之间的钒酸盐对蛙缝匠肌22Na外流的影响。当使用浓度低于0.5 mM的钒酸盐时，其添加没有效果；较高浓度会增加Na外流。添加哇巴因（10(-5)M）可消除这种增加。在用哇巴因预处理的肌肉中，钒酸盐不会改变Na外流。在无Na溶液中也观察到了钒酸盐对Na外流的刺激作用，这表明钒酸盐引起的外流增加主要不是由Na与Na交换的增加或Na进入肌肉的增加所导致的。我们还研究了钒酸盐对浸泡在含有20 mM K+溶液中的肌肉的影响；钒酸盐和增加的K+都对Na外流产生了相加的刺激作用。同样，当测量钒酸盐和胰岛素对同一块肌肉Na外流的影响时，也发现了相加作用。由于蛙肌中哇巴因敏感的Na外流通常被认为是由于Na-K ATP酶的活性，我们的研究结果表明钒酸盐在完整肌肉细胞中的净效应是增加Na泵的活性。由于钒酸盐会影响许多酶，很可能这种刺激作用不是由于对Na-K ATP酶的直接作用，而是可能通过一个中间步骤介导的。（摘要截短于250字）
