Rübsamen K, Engelhardt W V
Am J Physiol. 1978 Jul;235(1):E1-6. doi: 10.1152/ajpendo.1978.235.1.E1.
Bicarbonate appearance in the lumen and its relationship to solute absorption were studied in a Pavlov pouch in the cardiac region of the first compartment of the llama forestomach. HCO3- appearance showed no diurnal variation. HCO3- accumulation was highly dependent on the pH of the solution used. The HCO3- ion probably is formed from CO2 diffusing into the lumen from the serosal side, as a result of cell metabolism and of OH- ions. HCO3- accumulation was closely related to volatile fatty acid (VFA) absorption. The ratio of HCO3- appearance to VFA absorption depended on the pH of the solution. At a pH of 6.6, about 0.1 mol HCO3- and, at a pH of 7.8, 0.9 mol HCO3- appeared per mole absorbed VFA, indicating that at slightly alkaline pH nearly all H+ ions required for the nonionic absorption of VFA appeared to be delivered from the dissociation of H2CO3. Bicarbonate gain and VFA absorption were increased when animals were not fed for 48 h. Sodium absorption was related to VFA as well as water absorption.
对羊驼前胃第一隔室贲门区的巴甫洛夫小胃中的管腔内碳酸氢盐的出现情况及其与溶质吸收的关系进行了研究。HCO₃⁻的出现没有昼夜变化。HCO₃⁻的积累高度依赖于所用溶液的pH值。HCO₃⁻离子可能是由于细胞代谢产生的OH⁻离子以及CO₂从浆膜侧扩散到管腔中而形成的。HCO₃⁻的积累与挥发性脂肪酸（VFA）的吸收密切相关。HCO₃⁻出现量与VFA吸收量的比值取决于溶液的pH值。在pH值为6.6时，每吸收1摩尔VFA约有0.1摩尔HCO₃⁻出现，在pH值为7.8时，每吸收1摩尔VFA有0.9摩尔HCO₃⁻出现，这表明在略碱性的pH值下，VFA非离子吸收所需的几乎所有H⁺离子似乎都来自H₂CO₃的解离。当动物禁食48小时时，碳酸氢盐的增加和VFA的吸收都会增加。钠的吸收与VFA以及水的吸收有关。
