Sernka T J, Tseng C H
Gen Physiol Biophys. 1985 Feb;4(1):69-80.
The effect of caffeine on the transport, metabolism and ultrastructure of the colon were determined. Segments of proximal colon were excised from the anesthetized rat and prepared for radioisotopic tracing of ion transport in the flux chambers or oxidative metabolism in an incubator. Other segments were fixed before or after caffeine administration for electron microscopy. The isolated rat colon actively transported both Na+ and Cl- in the absorptive direction, mucosa to serosa. Serosal addition of 10 mmol/l caffeine abolished the smaller Na+ transport but did not significantly affect the larger Cl- transport. The electrical potential difference and the short-circuit current rose accordingly. Although the oxidation of glucose was inhibited by 35%, caffeine had no significant effect on the oxidation of the fatty acid, butyric acid. Comparable metabolic responses were obtained using the isolated terminal ileum of the rat. Neither the height nor the density of the microvilli in the proximal colon were affected significantly by caffeine. It may be concluded that caffeine, unlike theophylline, effectively preserves the normal absorptive condition of the colon. Thus, caffeine may have actions other than inhibition of phosphodiesterase in the distal intestine.
研究了咖啡因对结肠转运、代谢及超微结构的影响。从麻醉大鼠身上切除近端结肠段，制备用于在通量室中进行离子转运放射性同位素示踪或在培养箱中进行氧化代谢研究的样本。其他结肠段在给予咖啡因之前或之后进行固定，用于电子显微镜观察。分离的大鼠结肠在吸收方向（从黏膜到浆膜）上主动转运Na⁺和Cl⁻。在浆膜侧添加10 mmol/L咖啡因可消除较小的Na⁺转运，但对较大的Cl⁻转运无显著影响。电位差和短路电流相应升高。虽然葡萄糖氧化受到35%的抑制，但咖啡因对脂肪酸丁酸的氧化无显著影响。使用大鼠分离的回肠末端可获得类似的代谢反应。咖啡因对近端结肠微绒毛的高度和密度均无显著影响。可以得出结论，与茶碱不同，咖啡因能有效维持结肠的正常吸收状态。因此，咖啡因在远端肠道可能具有除抑制磷酸二酯酶以外的其他作用。
