ACTIVE POTASSIUM TRANSPORT BY THE ISOLATED LEPIDOPTERAN LARVAL MIDGUT: STIMULATION OF NET POTASSIUM FLUX AND ELIMINATION OF THE SLOWER PHASE DECLINE OF THE SHORT-CIRCUIT CURRENT
ACTIVE POTASSIUM TRANSPORT BY THE ISOLATED LEPIDOPTERAN LARVAL MIDGUT: STIMULATION OF NET POTASSIUM FLUX AND ELIMINATION OF THE SLOWER PHASE DECLINE OF THE SHORT-CIRCUIT CURRENT
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孤立鳞翅目幼虫中肠的活性钾运输：刺激净钾通量并消除短路电流的缓慢阶段下降
DOI：
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发表时间：
1983
期刊：
影响因子：
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通讯作者：
K. Giangiacomo
中科院分区：
文献类型：
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作者：
M. G. Wolfersberger;K. Giangiacomo
内容提要1.用短路电流(SCC)法检测了腺苷3‘：5’-环磷酸(CAMP)、抗生素A23187、咖啡因、霍乱毒素、二丁酰环一磷酸(DBcAMP)、5-羟色胺(5-HT)、幼虫血液和茶碱对幼虫中肠主动钾转运的影响。2.在短路电流正常指数下降的快速阶段，受试材料对短路电流没有影响，而在指数下降的较慢阶段，只有DBcAMP和幼虫血影响短路电流。3.二丁基环AMP可增加细胞的短路电流和净钾离子通量(用42K测量)。两个方向的钾素通量都有所增加，但对通量比和钾素净运转率随时间的变化没有影响。4.五龄幼虫血液的透析物对钾的转运作用与DBcAMP相似，表明幼虫血液中含有天然的转运刺激因子。5.四龄幼虫血液的可透析提取物不仅能促进钾离子的转运，而且能阻止短路电流的缓慢下降。因此，除了5龄幼虫血液中存在的运输刺激因子外，4龄幼虫血液中似乎还含有一些物质，这些物质至少在体外可以防止中肠运输相关功能的退化。6.认为幼虫血液中运输刺激因子对幼虫中肠细胞生电阳离子泵的作用是由环磷酸腺苷介导的，而不涉及细胞内钙离子浓度的变化。
SUMMARY 1. Adenosine 3':5'-cyclic monophosphate (cyclic AMP), Antibiotic A23187, caffeine, cholera toxin, dibutyryladenosine 3' :5'-cyclic monophosphate (dbcAMP), 5-hydroxytryptamine (5-HT), larval blood, and theophylline were tested for their effects on active potassium transport, as measured by the short-circuit current (SCC), in isolated Manduca sext a larval midgut. 2. None of the tested materials affected the short-circuit current during the rapid phase of its usual exponential decline, and only dbcAMP and larval blood affected the short-circuit current during the slower phase of its exponential decline. 3. Dibutyryl-cyclic AMP stimulated an increase in short-circuit current and net potassium flux (measured using 42 K). Both unidirectional potassium fluxes increased but there was no effect on the flux ratio or on the rate at which net potassium transport declined with time. 4. A dialysable extract of fifth instar larval blood effected potassium transport in a manner similar to that of dbcAMP, indicating that larval blood contains natural transport-stimulating factors. 5. A dialysable extract of fourth instar larval blood not only stimulated potassium transport but also prevented the slow phase of decline in the short-circuit current. Therefore, in addition to transport-stimulating factors present in fifth instar blood, fourth instar blood appears to contain substances which prevent degeneration of at least the transport related functions of midgut in vitro. 6. It is argued that the action of the transport-stimulating factor in larval blood on the electrogenic cation pump in larval midgut cells is mediated by cyclic AMP without involving a change in intracellular calcium ion concentration.