Pathways of Intestinal Absorption and Their Ecological Significance

一个普遍的概念是糖（D-葡萄糖）主要被肠主动吸收。然而，Pi的证据表明，鸟类可以吸收大量的另一种形式的葡萄糖，L-葡萄糖，这被认为是被动吸收，而不是主动吸收。拟议的研究测试的假设，L-葡萄糖是被动吸收的鸟类，并推断，大多数D-葡萄糖的吸收是被动的。 这些研究还将确定如何 鸟类肠道的被动吸收随水溶性分子的大小而变化， 运动 吸收的溶质发生在肠细胞之间。 的 结果 将 被 重要 到 生理学家进化生物学家毒理学家和生态学家 大多数糖是被动吸收的这一发现将是重要的 因为 它 将 挑战 关于营养吸收的流行生理学观点，以及试图与吸收营养的生理能力相匹配的进化消化生理学的当前分析 与 营养摄入量 一 高 允许被动吸收的肠渗透性可能允许毒素从肠中的植物和动物材料吸收。 这种情况需要研究 对 与自然毒素的接触和解毒有关的生态成本，以及野生动物对人类生产的新一代水溶性除草剂和杀虫剂的敏感性。

Karasov 9723793 A widespread notion is that sugar (D-glucose) is mainly actively absorbed by the intestine. The Pi's have evidence, however, that birds can absorb considerable amounts of the other form of glucose, L-glucose, which is thought to be absorbed passively, not actively. The proposed studies test the assumption that L-glucose is absorption passively by birds, and the inference that most D-glucose absorption is passive. The studies will also determine how passive absorption by the avian intestine varies with size of water-soluble molecules, and whether the movement of absorbed solutes occurs across or between intestinal cells. The findings will be important to physiologists, evolutionary biologists, toxicologists, and ecologists. A finding that most sugar is absorbed passively would be important because it would challenge prevailing physiological ideas about nutrient absorption as well as current analyses in evolutionary digestive physiology that attempt to match the physiological capacity to absorb nutrients with nutrient intake. A high intestinal permeability permitting passive absorption might permit toxins to be absorbed from plant and animal material in the intestine. This scenario would beg research on the ecological cost associated with exposure and detoxication of natural toxins, and perhaps the sensitivity of wild animals to the new generation of water-soluble herbicides and pesticides produced by humans.