Department of Gastroenterology, Hepatology, and Endocrinology, Hannover Medical School, Hannover, Germany.
Biol Pharm Bull. 2011;34(6):794-802. doi: 10.1248/bpb.34.794.
A number of transport mechanisms in the colonic epithelium contribute to HCO₃⁻ movement across the apical and basolateral membranes, but this ion has been largely regarded as a by-product of the transport functions it is involved in, such as NaCl or short chain fatty acid (SCFA) absorption. However, emerging data points to several specific roles of HCO₃⁻ for colonic epithelial physiology, including pH control in the colonic surface microenvironment, which is important for transport and immune functions, as well as the secretion and the rheological properties of the mucus gel. Furthermore, recent studies have demonstrated that colonic HCO₃⁻ transporters are expressed in a highly segmental as well as species-specific manner. This review summarizes recently gathered information on the functional anatomy of the colon, the roles of HCO₃⁻ in the colonic epithelium, colonic mucosal integrity, and the expression and function of HCO₃⁻ transporting mechanisms in health and disease.
肠道上皮中的多种转运机制有助于 HCO₃⁻穿过顶端和基底外侧膜的运动，但这种离子在很大程度上被视为其参与的转运功能（如 NaCl 或短链脂肪酸 [SCFA] 吸收）的副产物。然而，新出现的数据表明 HCO₃⁻对结肠上皮生理学具有几个特定的作用，包括控制结肠表面微环境中的 pH 值，这对于转运和免疫功能很重要，以及黏液凝胶的分泌和流变性质。此外，最近的研究表明，HCO₃⁻转运蛋白在结肠中以高度节段和物种特异性的方式表达。本综述总结了最近关于结肠功能解剖、HCO₃⁻在结肠上皮中的作用、结肠黏膜完整性以及 HCO₃⁻转运机制在健康和疾病中的表达和功能的信息。
