Machin J
Am J Physiol. 1983 Feb;244(2):R187-92. doi: 10.1152/ajpregu.1983.244.2.R187.
In common with other animals the principal examples of water transport in insects are to be found in processing food and in excretion. Some insects and other arthropods are able to absorb water vapor using preexisting buccal or rectal structures. This unique exploitation of atmospheric water depends on adequate areas for condensing water vapor and the capacity for considerable "uphill" water transport. All known uptake mechanisms depend on producing fluids of sufficiently low water activity to bring about condensation from a range of environmental humidities. In the best-understood examples (mealworms and their relatives) active KCl transport by the Malpighian tubules generates osmotic pressures sufficient to extract water from activities down to 0.88. A standing gradient model seems to describe the coupling in the tubular lumen between water flows and ion transport. Low water permeabilities and ion transport modulated with flow rate are unusual features of this coupling.
与其他动物一样，昆虫体内水分运输的主要例子见于食物处理和排泄过程中。一些昆虫和其他节肢动物能够利用现有的口腔或直肠结构吸收水蒸气。这种对大气中水分的独特利用方式依赖于足够的水蒸气凝结面积以及相当大的“向上”水分运输能力。所有已知的摄取机制都依赖于产生水活性足够低的液体，以便在一定范围的环境湿度下实现凝结。在最被深入研究的例子（黄粉虫及其同类）中，马氏管主动运输氯化钾产生的渗透压足以从水活性低至0.88的环境中提取水分。一个稳态梯度模型似乎可以描述管腔内水流与离子运输之间的耦合关系。低水渗透性以及随流速调节的离子运输是这种耦合关系的独特特征。
