title: The effect of hypoosmolarity on the electrical properties of Madin Darby canine kidney cells.
abstract: The present study has been performed to test for the effect of hypotonic extracellular fluid on the electrical properties of Madin Darby canine kidney (MDCK)-cells. The volume of suspended MDCK-cells is 1,892 +/- 16 fl (n = 8) in isotonic (298.7 mosmol/l) extracellular fluid. Exposure of the cells to hypotonic (230.7 mosmol/l) extracellular fluid is followed by cellular swelling to 2,269 +/- 18 fl (n = 4) and subsequent volume regulatory decrease to 2,052 +/- 22 fl (n = 4) within 512 s. Volume regulatory decrease is abolished by quinidine (1 mmol/l) and by lipoxygenase inhibitor nordihydroguaiaretic acid (50 mumol/l). The potential difference across the cell membrane averages -53.6 +/- 0.9 mV (n = 49) in isotonic extracellular perfusates. Reduction of extracellular osmolarity depolarizes the cell membrane by +25.7 +/- 0.8 mV (n = 67), reduces the apparent potassium selectivity of the cell membrane, from 0.55 +/- 0.07 (n = 9) to 0.09 +/- 0.01 (n = 26), and increases the apparent chloride selectivity from close to zero to 0.34 +/- 0.02 (n = 21). Potassium channel blocker barium (1 mmol/l) depolarizes the cell membrane by +15.2 +/- 1.1 mV (n = 13). In the presence of barium, reduction of extracellular osmolarity leads to a further depolarization by +14.0 +/- 1.4 mV (n = 12). Addition of chloride channel blocker anthracene-9-COOH (1 mmol/l) leads to a hyperpolarization of the cell membrane by -6.7 +/- 2.2 mV (n = 11). In the presence of anthracene-9-COOH, reduction of the extracellular osmolarity leads to a depolarization by +22.4 +/- 1.7 mV (n = 11).(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Institut für Physiologie, Universität Innsbruck, Austria.
authors: M
authors: M
authors: Paulmichl
authors: F
authors: F
authors: Friedrich
authors: K
authors: K
authors: Maly
authors: F
authors: F
authors: Lang
mesh_terms: D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D001464:Barium / Q000494:pharmacology; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism; D015289:Leukotrienes / Q000502:physiology; D009637:Masoprocol / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009994:Osmolar Concentration; D015221:Potassium Channels / Q000378:metabolism; D011802:Quinidine / Q000494:pharmacology
chemical_list: D000873:Anthracenes; D002712:Chlorides; D007473:Ion Channels; D015289:Leukotrienes; D015221:Potassium Channels; D001464:Barium; C010030:9-anthroic acid; D009637:Masoprocol; D011802:Quinidine