Keefee E B, Scharschmidt B F, Blankenship N M, Ockner R K
J Clin Invest. 1979 Dec;64(6):1590-8. doi: 10.1172/JCI109620.
Liver plasma membrane (LPM) NaK-ATPase activity, LPM fluidity, and bile acid-independent flow (BAIF) were studied in rats pretreated with one of five experimental agents. Compared with controls, BAIF was increased 24.6% by thyroid hormone and 34.4% by phenobarbital, decreased by ethinyl estradiol, but unchanged by propylene glycol and cortisone acetate. Parallel to the observed changes in BAIF, NaK-ATPase activity also was increased by thyroid hormone (40.8%) and decreased by ethinyl estradiol (26.2%). In contrast, NaK-ATPase activity failed to increase after phenobarbital but did increase 36% after propylene glycol and 34.8% after cortisone acetate. Thus BAIF and NaK-ATPase activity did not always change in parallel. The NaK-ATPase K(m) for ATP was not affected by any of these agents.LPM fluidity, measured by fluorescence polarization using the probe 1,6-diphenyl-1,3,5-hexatriene, was found to be increased by propylene glycol, thyroid hormone, and cortisone acetate, decreased by ethinyl estradiol, and unaffected by phenobarbital. Thus in these cases, induced changes in LPM fluidity paralleled those in NaK-ATPase activity. In no case did Mg-ATPase or 5'-nucleotidase activities change in the same direction as NaK-ATPase, and the activity of neither of these enzymes correlated with LPM fluidity, thus indicating the selective nature of the changes in LPM enzyme activity caused by the agents. These findings indicate that LPM fluidity correlates with NaK-ATPase activity and may influence the activity of this enzyme. However, the nature of the role of LPM NaK-ATPase in bile secretion is uncertain and needs further study.
对用五种实验药物之一预处理的大鼠的肝细胞膜（LPM）钠钾 - ATP酶活性、LPM流动性和非胆汁酸依赖性胆汁流（BAIF）进行了研究。与对照组相比，甲状腺激素使BAIF增加24.6%，苯巴比妥使BAIF增加34.4%，乙炔雌二醇使BAIF降低，而丙二醇和醋酸可的松对BAIF无影响。与观察到的BAIF变化平行，甲状腺激素使钠钾 - ATP酶活性增加（40.8%），乙炔雌二醇使钠钾 - ATP酶活性降低（26.2%）。相比之下，苯巴比妥处理后钠钾 - ATP酶活性未增加，但丙二醇处理后增加36%，醋酸可的松处理后增加34.8%。因此，BAIF和钠钾 - ATP酶活性并非总是平行变化。这些药物中的任何一种均未影响钠钾 - ATP酶对ATP的米氏常数（K(m)）。使用探针1,6 - 二苯基 - 1,3,5 - 己三烯通过荧光偏振测量的LPM流动性，发现丙二醇、甲状腺激素和醋酸可的松使其增加，乙炔雌二醇使其降低，苯巴比妥对其无影响。因此，在这些情况下，诱导的LPM流动性变化与钠钾 - ATP酶活性变化平行。在任何情况下，镁 - ATP酶或5'-核苷酸酶活性均未与钠钾 - ATP酶朝相同方向变化，且这两种酶的活性均与LPM流动性无关，从而表明这些药物引起的LPM酶活性变化具有选择性。这些发现表明，LPM流动性与钠钾 - ATP酶活性相关，并可能影响该酶的活性。然而，LPM钠钾 - ATP酶在胆汁分泌中的作用性质尚不确定，需要进一步研究。
