Ezzat Ahmed Ahmed
Department of Biology, College of Science, King Khalid University, 61413 Abha, Asir, Saudi Arabia.
EXCLI J. 2020 Aug 31;19:1208-1210. doi: 10.17179/excli2020-2836. eCollection 2020.
One of the central functions of the liver is excretion of bile into the intestine. Currently, bile excretion is explained by the osmotic model, according to which bile acids are excreted by hepatocytes into the bile canaliculi and since bile acids are osmotically active they draw water into the canalicular lumen. Bile canaliculi are closed at the central side. Therefore, bile was postulated to flow to the open side into the ducts. However, bile flow in canaliculi has never been measured because of the small canalicular diameter which does not allow analysis of flux by conventional methods. Recently, methods have been developed that allow flow analysis in bile canaliculi and ducts. Interestingly, no measurable directed flow was observed in the canaliculi. Instead, small molecules in bile canaliculi reached the larger bile ducts by diffusion. Only there measurable flow sets in. The pathophysiological implications of this novel observation are discussed.
肝脏的核心功能之一是将胆汁排泄到肠道。目前，胆汁排泄是通过渗透模型来解释的，根据该模型，肝细胞将胆汁酸排泄到胆小管中，由于胆汁酸具有渗透活性，它们会将水吸入胆小管腔。胆小管在中央侧是封闭的。因此，推测胆汁会流向开放侧进入胆管。然而，由于胆小管直径太小，无法用传统方法分析通量，所以从未测量过胆小管内的胆汁流动。最近，已经开发出了能够分析胆小管和胆管内流动的方法。有趣的是，在胆小管中未观察到可测量的定向流动。相反，胆小管中的小分子通过扩散进入较大的胆管。只有在胆管中才会出现可测量的流动。本文讨论了这一新发现的病理生理学意义。
