Influence of extracellular bicarbonate on the short-circuit current and intracellular free calcium of human cultured sweat duct cells.
Transepithelial short-circuit current (Iscc) and intracellular free Ca2+ (Ca2+i) was studied in monolayers of cultured human sweat duct cells (CSDCs) in the presence or absence of HCO3- (and CO2) in the bathing solutions. Addition of HCO3- (and CO2) increased the control Iscc by more than 50%. The effect of HCO3- (and CO2) on Iscc was confined to the serosal bath. The HCO3- (and CO2) effect was also studied during stimulation with the cholinergic agonist methacholine (MCh), which in CSDC induces a complex response consisting of an initial Iscc and Ca2+i spike, which is independent of extracellular Ca2+, followed by regular Iscc and Ca2+i oscillations, which are absent during Ca(2+)-free bathing conditions. The sustained Iscc and Ca2+i oscillations, but not the initial Iscc and Ca2+i spike were abolished by the removal of extracellular HCO3- (and CO2). It is concluded that the Ca2+ influx and the Iscc in CSDCs are critically influenced by the presence of extracellular HCO3- (and CO2) in the bathing solutions.
Pedersen
P S
PS
Department of Pediatrics, Rigshospitalet Copenhagen, Denmark.
D000584:Amiloride / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism* / Q000494:pharmacology; D002021:Buffers; D002118:Calcium / Q000502:physiology*; D002478:Cells, Cultured; D004594:Electrophysiology; D005110:Extracellular Space / Q000378:metabolism*; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D016210:Methacholine Chloride / Q000494:pharmacology; D013545:Sweat Glands / Q000166:cytology / Q000378:metabolism*
D001639:Bicarbonates; D002021:Buffers; D016210:Methacholine Chloride; D000584:Amiloride; D002118:Calcium