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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    The journal of membrane biology 123 (1991), S. 33-41 
    ISSN: 1432-1424
    Schlagwort(e): eccrine ; sweat gland ; cell volume ; cholinergic ; Ca ; potassium ; chloride ; channels ; quinidine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary The goal of the present study was to elucidate the ionic mechanisms by which cholinergic stimulation induces cell shrinkage in eccrine clear cells. Dissociated Rhesus monkey eccrine sweat clear cells were prepared by collagenase digestion of freshly isolated secretory coils and immobilized on a glass slide in a perfusion chamber at 30°C. The cell was visualized by light microscopy with differential interference contract (DIC) and was recorded with a video system (15,000× total magnification). The cell volume was calculated from the maximal cross section of the cell. Methacholine (MCh)-induced cell shrinkage, which was as much as 30% of resting cell volume, was dose dependent and pharmacologically specific. MCh-induced cell shrinkage was persistent in some cells but tended to partially wane with time in others. MCh-induced cell shrinkage was dependent on the chemical potential gradient for KCl, i.e., increasing [K] in the bath ([K] o ) from 5 to 120mm caused MCh to induce cell swelling, whereas removing [Cl] o at 120mm K partially restored the MCh-induced cell shrinkage. The interpolated null [K] o (medium [K] where the cell volume did not change by MCh) of 71mm agreed with the predicted [K] o,null. MCh-induced cell shrinkage was inhibited completely by 1mm quinidine (K-channel blocker) and partially by 1mm diphenylamine-2-carboxylic acid (DPC, a Cl-channel blocker), but not by 0.1mm ouabain or 0.1mm bumetanide, suggesting that MCh-induced cell shrinkage may be due to activation of both K and Cl channels with the resultant net KCl efflux down the chemical potential gradient. That Ca/calmodulin may be involved in cholinergic regulation of Cl and K channels is suggested because 10 μm ionomycin also induced cell shrinkage, MCh failed to induce cell shrinkage in a Ca-free medium after the endogenous Ca store was depleted, and (6-aminohexyl)-5-chlorol-naphthalenesulfonamide (W-7, a putative inhibitor of calmodulin) also inhibited MCh-induced cell shrinkage in a reversible manner.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 14 (1992), S. 246-252 
    ISSN: 1432-0789
    Schlagwort(e): Volcanic ash soil ; Fluorescent pseudomonads ; Rhizosphere ; Wheat ; Bacterial groups ; Phosphate fertilizer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Populations of several bacterial groups on the root surface of wheat and in root-free soil were investigated in volcanic ash soil and non-volcanic ash soil throughout a series of predetermined intervals. Over time, the populations changed similarly both on the root surface and in root-free soil. The numbers of total bacteria, fluorescent Pseudomonas spp., phosphate-solubilizing bacteria, and NH inf+ sup4 -oxidizing bacteria, were consistently lower in the plots with volcanic ash soil than with nonvolcanic ash soil, but the numbers of cellulose-decomposing bacteria were opposite to those of the other groups. Superphosphate application improved the growth of wheat in the volvanic ash soil. It did not, however, bring about any significant changes in the bacterial populations among the volcanic ash soils supplemented with three different levels of superphosphate, though there were some variations with plant age.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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