Effects of dietary or injected organic cations on larval Drosophila melanogaster:: Mortality and elimination of tetraethylammonium from the hemolymph
Effects of dietary or injected organic cations on larval Drosophila melanogaster:: Mortality and elimination of tetraethylammonium from the hemolymph
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DOI：
10.1002/arch.20085
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发表时间：
2005-10-01
影响因子：
2.2
通讯作者：
O'Donnell, MJ
中科院分区：
文献类型：
--
作者：
Bijelic, G;Kim, NR;O'Donnell, MJ
本研究的果蝇幼虫melonogaster检查的影响，注射原型有机阳离子四乙基铵（TEA）的血腔或添加TEA和/或其他有机阳离子的饮食。测量死亡率、血淋巴TEA水平和马氏管TEA分泌率。饮食TEA的LD 50为158.4 mM，如果饮食中也包括有机阳离子转运蛋白的竞争性抑制剂，则死亡率增加。死亡率从单独TEA（100 mM）的24%增加到83和67%时，饮食中含有TEA和奎尼丁（10 mM）的西咪替丁（100 mM），分别。TEA选择性微电极测量表明，在富含TEA的饲料中维持24小时的幼虫血淋巴TEA浓度约为饲料中TEA浓度的3%。从暴露于饮食TEA的幼虫分离的Molpighian小管比从喂食无TEA饮食的对照组的小管分泌更多的TEA。然而，摄入或注射TEA到血腔后血淋巴TEA浓度的下降速率大于肠道和马氏管（MT）主动运输速率所能解释的。我们建议，TEA浓度降低血淋巴矿石不仅通过主动运输跨MT和肠道，但也扩散到肠道。后一种途径是特别重要的，当幼虫以前保持在TEA丰富的饮食转移到一个TEA免费的饮食。摄入不含TEA的食物不仅可以清除肠腔，还可以形成一个不含TEA的隔室，TEA可以被动地从血淋巴扩散到其中。
This study of larval Drosophila melonogaster examined the effects of injecting the prototypical organic cation tetroethylammonium (TEA) into the hemocoel or adding TEA and/or other organic cations to the diet. Mortality, hemolymph TEA levels, and Malpighian tubule TEA secretion rates were measured. The LD50 for dietary TEA was 158.4 mM and mortality increased if competitive inhibitors of organic cation transporters were also included in the diet. Mortality increased from 24% on TEA (100 mM) alone to 83 and 67% when the diet contained both TEA and quinidine (10 mM) of cimetidine (100 mM), respectively. TEA-selective microelectrode measurements indicated that hemolymph TEA concentration was approximate to 3% of that in the diet for larvae maintained on TEA-enriched diet for 24 h. Molpighian tubules isolated from larvae exposed to dietary TEA excreted more TEA than did tubules from controls fed a TEA-free diet. However, the rate of decline of hemolymph TEA concentration following ingestion or injection of TEA into the hemocoel was greater than that explicable by rates of active transport by the gut and Malpighian tubules (MTs). We propose that TEA concentrations in the hemolymph ore reduced not only by active transport across the MTs and gut, but also by diffusion into the gut. The latter pathway is particularly important when larvae previously maintained upon TEA-enriched diet are transferred to a TEA-free diet. The ingestion of TEA-free food not only clears the gut lumen, but also creates a TEA-free compartment into which TEA may passively diffuse from the hemolymph.