Department of Biology, York University, Toronto, ON, Canada.
J Exp Biol. 2011 Dec 1;214(Pt 23):3992-9. doi: 10.1242/jeb.063719.
The anal papillae of freshwater mosquito larvae are important sites of NaCl uptake, thereby acting to offset the dilution of the hemolymph by the dilute habitat. The ion-transport mechanisms in the anal papillae are not well understood. In this study, the scanning ion-selective electrode technique (SIET) was utilized to measure ion fluxes at the anal papillae, and pharmacological inhibitors of ion transport were utilized to identify ion-transport mechanisms. Na(+) uptake by the anal papillae was inhibited by bafilomycin and phenamil but not by HMA. Cl(-) uptake was inhibited by methazolamide, SITS and DIDS but not by bafilomycin. H(+) secretion was inhibited by bafilomycin and methazolamide. Ouabain and bumetanide had no effect on NaCl uptake or H(+) secretion. Together, the results suggest that Na(+) uptake at the apical membrane occurs through a Na(+) channel that is driven by a V-type H(+)-ATPase and that Cl(-) uptake occurs through a Cl(-)/HCO(3)(-) exchanger, with carbonic anhydrase providing H(+) and HCO(3)(-) to the V-type H(+)-ATPase and exchanger, respectively.
淡水蚊子幼虫的肛门乳突是 NaCl 吸收的重要部位，从而可以抵消因栖息地稀释而导致的血淋巴稀释。肛门乳突中的离子转运机制还不是很清楚。在这项研究中，我们利用扫描离子选择性电极技术（SIET）来测量肛门乳突处的离子通量，并利用离子转运的药理学抑制剂来鉴定离子转运机制。巴弗洛霉素和苯甲脒可以抑制肛门乳突对 Na+的摄取，但 HMA 则不能。甲唑胺、SITS 和 DIDS 可以抑制 Cl-摄取，但巴弗洛霉素则不能。巴弗洛霉素和甲唑胺可以抑制 H+分泌。哇巴因和布美他尼对 NaCl 摄取或 H+分泌没有影响。综上所述，研究结果表明，顶端膜上的 Na+摄取是通过一种由 V 型 H+-ATP 酶驱动的 Na+通道进行的，而 Cl-摄取则是通过一种 Cl-/HCO3-交换器进行的，其中碳酸酐酶分别为 V 型 H+-ATP 酶和交换器提供 H+和 HCO3-。
