Electron probe X-ray microanalysis of cellular ions in the eccrine secretory coil cells during methacholine stimulation.
Intracellular concentrations of Na, K, Cl ([Na], [K] and [Cl], respectively) and other elements were determined in isolated monkey eccrine sweat secretory coil cells using quantitative electron probe X-ray microanalysis of freeze dried cryosections. The validity of the methodology was partially supported by qualitative agreement of the X-ray microanalysis data with those obtained by micro-titration with a helium glow spectrophotometer. [Na], [K] and [Cl] of the cytoplasm were the same as those in the nucleus in both clear and dark cells. [Na], [K], and [Cl] of the clear cells were also the same as those of the dark cells at rest and after stimulation with methacholine (MCh), suggesting that these two cell types behave like a functional syncytium. MCh stimulation induced a pharmacologically specific, dose-dependent decrease in [K] and [Cl] (as much as 65%), and a 3.7-fold increase in [Na]. In myoepithelial cells, a similar change in [Na] and [K] was noted after MCh stimulation although the decrease in [Cl] was only 20%. The MCh-induced change in [Na], [K] and [Cl] was almost completely inhibited by removal of Ca2+ from the medium. 10(-4) M bumetanide inhibited the MCh-induced increase in [Na], reduced the decrease in [K] by about 50%, but slightly augmented the MCh-induced decrease in [Cl]. 10(-4) M ouabain increased [Na] and decreased [K] as did MCh; however, unlike MCh, ouabain increased [Cl] by 56% after 30 min of incubation. Thus the data may be best interpreted to indicate that Ca-dependent K efflux and (perhaps also Ca-dependent) Cl efflux are the predominant initial ionic movement in muscarinic cholinergic stimulation of the eccrine sweat secretory coils and that the ouabain-sensitive Na pump plays an important role in maintenance of intracellular ions and sweat secretion.
Saga
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Marshall Dermatology Research Laboratories, Department of Dermatology, University of Iowa College of Medicine, Iowa City 52242.
Sato
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K
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001692:Biological Transport; D002034:Bumetanide / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism; D004439:Eccrine Glands / Q000187:drug effects / Q000378:metabolism*; D004573:Electrolytes / Q000378:metabolism*; D004577:Electron Probe Microanalysis; D008253:Macaca mulatta; D016210:Methacholine Chloride; D008688:Methacholine Compounds / Q000494:pharmacology*; D013057:Spectrum Analysis / Q000379:methods; D013542:Sweat / Q000378:metabolism; D013545:Sweat Glands / Q000378:metabolism*
D004573:Electrolytes; D008688:Methacholine Compounds; D016210:Methacholine Chloride; D002034:Bumetanide; D001285:Atropine; D002118:Calcium