液体イオン交換膜徴小電極による生体膜K,CIイオン転送機構の研究

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タイトル別名
  • The Studies of Potassium and Chloride ion Transport Mechanisms Across the Biological Membrane using the Liquid ion Exchanger Microelectrodes
  • エキタイ イオン コウカン マク ビショウ デンキョク ニヨル セイタイ マク

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This study was attempted to clarify the transport mechanisms of K+ and Cl- across the toad urinary bladder epithelial cells using potassium sensitive and chloride sensitive liquid ion exchanger microelectrode (K+-microelectode and Cl--microelectrode). The characteristics of K+- and Cl--microelctrode were examined. The sensitivity slope(sRT/zFIn10) of K+- and Cl--microelectrode was 59.04±0.03 and -54.38±0.19 mV/10 fold of ionic activity, respectively. The selectivity constant of K+-microelectrode was 53.95±4.00 for K+/Na+ and 3.48±0.15 for K+/NH4+. And that of Cl--microelctrode was 8.00±0.15 for Cl-/HCO3- and 63.59±1.20 for Cl-/H2PO4-. Therefore each microeletrode was available to measure the intraccellular K+ or Cl- activity. The effect of ouabain, ethacrynic acid, ADH and PGE1 on the intracellular potassium ion activity (a1k) was studied, respectively. Simultaneous determinations of membrane potential difference across the bladder(PD), short circuit current(SCC), mucosal membrane potential(mEm) and serosal membrane potential (sEm) were done. The results suggested that there might be two different sodium pumps (ouabain sensitive Na-pump and ethacrynic acid sensitive, electrogenic Na-pump) and high intracellular potassium ion activity was maintained by the ouabain sensitive Na-pump. It was also suggested that ADH might stimulate the electrogenic Na-pump. On the other hand, PGE1 might stimulate the ouabain sensitive Na-pump. The effect of ouabain, ADH and serosal chloride concentration on the intracellular chloride ion activity (a1c1) was studied, respectively. The results showed that chloride transport seems to be electrochemically passive from mucosal to serosal and to be regulated by the serosal membrane potential. The intracellular chloride ion might play a role of the maintenance of intracellular electrical neutrality and facilitate the cation transport, so chloride ion might be regarded as a sort of balancing ion.

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