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|Title:||MAXI K+ CHANNELS IN THE BASOLATERAL MEMBRANE OF THE EXOCRINE FROG-SKIN GLAND REGULATED BY INTRACELLULAR CALCIUM AND PH||Authors:||Andersen, H.K.
VAN KERKHOVE, Emmy
|Issue Date:||1995||Publisher:||SPRINGER VERLAG||Source:||PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 431(1). p. 52-65||Abstract:||With the single-channel patch-clamp technique we have identified Ca2+-sensitive, high-conductance (maxi) K+ channels in the basolateral membrane (BLM) of exocrine gland cells in frog skin, Under resting conditions, maxi K+ channels were normally quiescent, but they were activated by muscarinic agonists or by high serosal K+. In excised inside-out patches and with symmetrical 140 mmol/l K+, single-channel conductance was 200 pS and the channel exhibited a high selectivity for K+ over Na+. Depolarization of the BLM increased maxi K+ channel activity. Increasing cytosolic free Ca2+ (by addition of 100 nmol/l thapsigargin to the bathing solution of cell-attached patches also increased channel activity, whereas thapsigargin had no effect when added to excised inside-out patches, An increase in cytosolic free Ca2+ directly activated channel activity in a voltage-dependent manner, Maxi K+ channel activity was sensitive to changes in intracellular pH, with maximal activity at pH 7.4 and decreasing activities following acidification and alkalinization. Maxi K+ channel outward current was reversibly blocked by micromolar concentrations of Ba2+ from the cytosolic and extracellular site, and was irreversibly blocked by micromolar concentrations of charybdotoxin and kaliotoxin from the extracellular site in outside-out patches.||Notes:||NATL UNIV IRELAND UNIV COLL CORK,DEPT PHYSIOL,CELLULAR PHYSIOL RES UNIT,CORK,IRELAND. LIMBURGS UNIV CENTRUM,DEPT MBW FYSIOL,B-3590 DIEPENBEEK,BELGIUM.ANDERSEN, HK, AUGUST KROGH INST,ZOOPHYSIOL LAB,UNIV PK 13,DK-2100 COPENHAGEN O,DENMARK.||Keywords:||CALCIUM; FROG SKIN GLANDS; MAXI K+ CHANNEL; PATCH CLAMP; PH; THAPSIGARGIN||Document URI:||http://hdl.handle.net/1942/3516||ISI #:||A1995TG33200007||Type:||Journal Contribution|
|Appears in Collections:||Research publications|
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