Active potassium transport across guinea-pig distal colon: action of secretagogues.
Active potassium transport across guinea-pig distal colon: action of secretagogues.
复制标题
穿过豚鼠远端结肠的活性钾转运：促分泌剂的作用。
DOI：
10.1113/jphysiol.1996.sp021398
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Halm,DR
中科院分区：
文献类型：
--
作者：
Rechkemmer,G;Frizzell,RA;Halm,DR
1.在离体豚鼠远端结肠上皮中，肾上腺素（5 μ M）刺激了2.2 μ equiv h-1 cm-2的K+分泌电流。这种分泌活性完全抑制添加袢利尿剂布美他尼的serovine解决方案。通过吸收途径进行的K+吸收未因这些变化而改变。2.前列腺素E2（PGE 2，2 μ M）分别刺激3.0和3.6 μ equiv h-1 cm-2的生电性K+分泌和Cl-分泌。添加布美他尼的丝氨酸完全抑制了这种K+分泌，但仅阻断了约70%的Cl-分泌。布美他尼不敏感的Cl-分泌电流取决于浴槽溶液中Cl-和HCO 3-的存在。3. PGE 2刺激产电性K+分泌的半最大浓度为4 nM，亲和力比PGE 2刺激Cl-分泌的亲和力高约300倍。4.毛喉素（10 μ M）刺激Cl-分泌4.9 μ equiv h-1 cm-2。表观K+分泌速率仅增加1.5 mu equiv h-1 cm-2。布美他尼不敏感短路电流（ISC）明显，且大小与PGE 2刺激的相同。5.在吲哚美辛（1 μ M）的存在下，加入Ca 2+离子载体A23187（10 μ M）以减少前列腺素的产生，抑制了40%的K+吸收途径，同时刺激了小速率的生电K+分泌。6.主动K+吸收抑制哇巴因，奥美拉唑或SCH 28080的粘膜溶液中加入。奥美拉唑和SCH 28080也刺激小的负ISC，与产电K+分泌一致。7. K+吸收、K+分泌和Cl-分泌之间的关联通过转运机制的相似性和促分泌素调节来表明。特别是，最大速率的K+分泌电流需要通过顶端膜K+泵摄取。这种相互关系支持这些离子转运途径的共同细胞位点。
1. Adrenaline (5 microM) stimulated a K+ secretory current by 2.2 mu equiv h‐1 cm‐2 in isolated guinea‐pig distal colonic epithelium. This secretory activity was inhibited entirely by addition of the loop diuretic bumetanide to the serosal solution. On‐going K+ uptake via the absorptive pathway was unaltered by these changes. 2. Prostaglandin E2 (PGE2, 2 microM) stimulated electrogenic K+ secretion and Cl‐ secretion by 3.0 and 3.6 mu equiv h‐1 cm‐2, respectively. Serosal addition of bumetanide completely inhibited this K+ secretion but blocked only approximately 70% of Cl‐ secretion. The bumetanide‐insensitive Cl‐ secretory current was dependent on the presence of Cl‐ and HCO3‐ in the bathing solutions. 3. Stimulation of electrogenic K+ secretion by PGE2 occurred with a half‐maximal concentration of 4 nM, an affinity approximately 300 times higher than that for stimulation of Cl‐ secretion by PGE2. 4. Forskolin (10 microM) stimulated Cl‐ secretion by 4.9 mu equiv h‐1 cm‐2. The apparent K+ secretory rate was increased by only 1.5 mu equiv h‐1 cm‐2. A bumetanide‐insensitive short‐circuit current (ISC) was apparent and of the same size as that stimulated by PGE2. 5. Addition of the Ca2+ ionophore A23187 (10 microM), in the presence of indomethacin (1 microM) to reduce prostaglandin production, inhibited the K+ absorptive pathway by 40% and concurrently stimulated a small rate of electrogenic K+ secretion. 6. Active K+ absorption was inhibited by the addition of ouabain, omeprazole or SCH28080 to the mucosal solution. Both omeprazole and SCH28080 also stimulated a small negative ISC, consistent with electrogenic K+ secretion. 7. Association of K+ absorption, K+ secretion and Cl‐ secretion is indicated by similarities in transport mechanism and by secretagogue regulation. In particular, maximal rates of K+ secretory current require uptake via apical membrane K+ pumps. Such interrelations support a common cellular locus for these ion transport pathways.