Grotmol T, Buanes T, Roeder M
University of Oslo, Institute for Experimental Medical Research, Norway.
Acta Physiol Scand. 1989 Jul;136(3):411-7. doi: 10.1111/j.1748-1716.1989.tb08682.x.
The present study was performed in anaesthetized pigs, and the first aim was to assess the role of Na,K-ATPase in secretin-dependent biliary HCO3 secretion (JbHCO3). Intra-arterial administration of the cardiac glycoside digitoxin (0.2 mg/kg-1) reduced hepatic Na K-ATPase activity, JbHCO3 and secretin-dependent bile flow by 24, 55 and 34% respectively. In the second part of this study lithium (Li) was used as a marker of passive Na transport to assess the electrochemical gradient for Na flux into bile duct lumen during secretin-stimulated bile flow and impeded biliary osmotic water flow by i.v. infusion of glucose. At plasma glucose 85 (73-96) mmol l-1, bile [Na] and [Li] exceeded their concentrations in plasma by 57 and 47% respectively. By using the Nernst equation, transepithelial potential difference (PD) during hyperglycaemia was estimated to be -6.2 (0 to -10.8) mV (ductal lumen negative), which corresponds to a [Li]bile/[Li]plasma ratio of 1.3 (1.0-1.5). The ratio was not significantly different from the observed [Li]bile/[Li]plasma ratio of 1.4 (1.3-1.5). It is concluded (1) that Na, K-ATPase is necessary for JbHCO3, probably by sustaining the cell membrane PD (cell interior negative) which is a driving force for apical electrogenic HCO3 secretion, and (2) transepithelial Li (and hence Na) flux is driven solely by the negative transcellular PD during secretin-stimulated bile flow in the pig.
本研究在麻醉猪身上进行，首要目的是评估钠钾ATP酶在促胰液素依赖性胆汁HCO₃分泌（JbHCO₃）中的作用。动脉内注射强心苷地高辛（0.2mg/kg⁻¹）分别使肝脏钠钾ATP酶活性、JbHCO₃和促胰液素依赖性胆汁流量降低了24%、55%和34%。在本研究的第二部分，锂（Li）被用作被动钠转运的标志物，以评估促胰液素刺激胆汁流动期间钠流入胆管腔的电化学梯度，并通过静脉输注葡萄糖来阻碍胆汁渗透水流。在血浆葡萄糖浓度为85（73 - 96）mmol/L时，胆汁中的[Na]和[Li]分别比血浆中的浓度高出57%和47%。通过使用能斯特方程，高血糖期间的跨上皮电位差（PD）估计为 -6.2（0至 -10.8）mV（导管腔为负），这对应于[Li]胆汁/[Li]血浆比值为1.3（1.0 - 1.5）。该比值与观察到的[Li]胆汁/[Li]血浆比值1.4（1.3 - 1.5）无显著差异。得出的结论是：（1）钠钾ATP酶对于JbHCO₃是必需的，可能是通过维持细胞膜电位差（细胞内部为负），这是顶端电生性HCO₃分泌的驱动力；（2）在猪促胰液素刺激胆汁流动期间，跨上皮锂（以及因此的钠）通量仅由负的跨细胞电位差驱动。
