Zemková H, Teisinger J, Vyskocil F
Institute of Physiology, Czechoslovak Academy of Sciences, Prague.
J Neurosci Res. 1988 Apr;19(4):497-503. doi: 10.1002/jnr.490190414.
The K+-induced hyperpolarization of Na-loaded mouse diaphragm muscle, enzymatic activity of Na,K-ATPase and 3H-ouabain binding to rat brain microsomes was measured in the presence of K+ channel blockers tetraethylammonium (TEA), tetrabutylammonium (TBA) and apamin. TBA, and to a lesser extent TEA in millimolar concentrations, inhibited the electrogenic effect of the Na,K pump, Na,K-ATPase activity, and 3H-ouabain binding. The inhibition of 3H-ouabain binding by TEA or TBA was more evident in the presence of ATP and Na+ ions. Apamin in nanomolar concentrations inhibited the electrogenic effect of Na,K pump and Na,K-ATPase but not the 3H-ouabain binding. The hyperpolarizing effects of insulin and NADH, but not that of noradrenaline, were also prevented by apamin. The inhibition of Na,K pump by TEA and TBA is apparently due to both competition with K+ for a binding site on the Na,K-ATPase and a reduction in the number of transporting sites. The site of action of apamin on Na,K-ATPase is different from that of tetra-alkylammonium compounds; it apparently decreases the turnover rate of the enzyme.
在存在钾通道阻滞剂四乙铵（TEA）、四丁铵（TBA）和蜂毒明肽的情况下，测量了钾离子诱导的钠负载小鼠膈肌的超极化、钠钾-ATP酶的酶活性以及3H-哇巴因与大鼠脑微粒体的结合。毫摩尔浓度的TBA以及在较小程度上的TEA，抑制了钠钾泵的电效应、钠钾-ATP酶活性和3H-哇巴因结合。在存在ATP和钠离子的情况下，TEA或TBA对3H-哇巴因结合的抑制作用更为明显。纳摩尔浓度的蜂毒明肽抑制了钠钾泵的电效应和钠钾-ATP酶，但不抑制3H-哇巴因结合。蜂毒明肽也阻止了胰岛素和NADH的超极化作用，但不阻止去甲肾上腺素的超极化作用。TEA和TBA对钠钾泵的抑制作用显然是由于它们与钾离子竞争钠钾-ATP酶上的结合位点以及转运位点数量的减少。蜂毒明肽对钠钾-ATP酶的作用位点与四烷基铵化合物不同；它显然降低了该酶的周转速率。
