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  • 1990-1994  (2)
  • 1900-1904
  • Ca  (1)
  • Cation-exchange preconcentration  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 123 (1991), S. 33-41 
    ISSN: 1432-1424
    Keywords: eccrine ; sweat gland ; cell volume ; cholinergic ; Ca ; potassium ; chloride ; channels ; quinidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Ion-interaction chromatography ; Cation-exchange preconcentration ; Yttrium and lanthanides ; Standard rock analysis ; Glycolatocomplexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method of applying ion-interaction chromatography to the determination of the rare earth elements in silicate rocks on a 100 to 200 mg sample basis has been developed. The rare earths are first separated as a group from matrices by cation-exchange chromatography in hydrochloric acid-thiocyanate media and isolated in a small, defined volume (3.00 ml). Using fractions of this, on-column concentration of the rare earths on a C-18 bonded phase silica coated with 1-octanesulfonate and a subsequent concentration gradient elution with glycolate (0.05 to 0.35 M) at pH 3.5 allows the respective separation of La, Ce, Pr, Nd, and Y (100 μl aliquot used) and of Er, Tm, Yb, and Lu (2.00 ml aliquot used). Sm, Eu, Gd, Tb, and Dy elute together, and Ho is not sufficiently well resolved from these middle rare earth elements. The eluted rare earth elements are detected and quantified by post-column reaction with Arsenazo III photometrically, using a UV-VIS spectrophotometer at a wavelength of 650 nm. The method is shown to be capable of determining nine of the rare earth elements in a variety of international reference rock samples with good precision and accuracy.
    Type of Medium: Electronic Resource
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