Electrical properties of cultured renal tubular cells (OK) grown in confluent monolayers |
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Authors: | Johann S Schwegler Almut Heuner Stefan Silbernagl |
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Institution: | (1) Physiologisches Institut, Universität Würzburg, Röntgenring 9, D-8700 Würzburg, Federal Republic of Germany |
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Abstract: | OK cells grown to confluent monolayers were investigated by microelectrode techniques and microinjection. Cell membrane potential difference (PDm) in bi-carbonate-free solution is –61.8±0.6 mV (n=208), cell membrane resistance (Rm) amounts to 1.4±0.2k · cm2 (n=8). The apparent transference number for potassium (tK
+) is 71±3% (n=28) and can be reduced by 3 mmol/l BaCl2 to 7.5±4.0%; (n=8). In the presence of extracellular CO2 and HCO
3
–
(pH 7.4) the cells acidify by 0.34±0.05 pH units (n=12). This leads to a depolarization of PDm by 8.4±1.8 mV (n=8), an increase in Rm by 49±10% (n= 10), and a reduction of K+-conductance to 63±5% (n= 13). Intracellular acidification by the NH4Cl-prepulse technique also inhibits K+-conductance and depolarizes the membrane. Recovery from an intracellular acid load is reflected by cell membrane repolarization. This recovery can be inhibited by amiloride (10–3 mol/l). Na+- and Cl–-conductances could not be detected.The transepithelial resistance (R
te) of OK cell monolayers 1 day after plating is 41±6 ·cm2 and decreases with time after plating. Intercellular communication (electrical or dye coupling) was not observed.Conclusions: 1. The membrane potential of OK cells is largely determined by a pH-sensitive, barium-blockable K+-conductance. 2. Amiloride-blockable Na+/H+-exchange is reflected by membrane potential changes via this K+-conductance. 3. Monolayers of OK cells are electrically leaky.Parts of this study were presented at the 66th meeting of the Deutsche Physiologische Gesellschaft, Würzburg, September 1988 Pflügers Arch 412 (Suppl 1):R55]. |
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Keywords: | K+-conductance OK cells Intercellular communication Intracellular pH |
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