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AJP - Regulatory, Integrative and Comparative Physiology, Vol 273, Issue 5 1719-R1725, Copyright © 1997 by American Physiological Society
ARTICLES |
B. Pelster and H. Niederstatter
Institut fur Zoologie, Universitat Innsbruck, Austria.
The pH dependence of acid production and of acid release has been analyzed in cultured gas gland cells of the European eel using a cytosensor microphysiometer. Total acid release of gas gland cells showed an optimum at pH 7.4-7.6, with only a minor reduction at acidic (pH 7.0) as well as at alkaline pH (pH 8.0). The acid production was largely dependent on the availability of extracellular glucose and was almost completely abolished if glucose was replaced by succinate, alanine, or even pyruvate. Phloretin, an inhibitor of glucose uptake, significantly reduced acid release of gas gland cells with a Ki of approximately 1 x 10(-5) M, irrespective of pH. Although the glucose dependence of acid production was not modified by pH, acid release became increasingly sodium dependent with decreasing pH, but at low pH significantly higher sodium concentrations were necessary to achieve maximal rate of proton secretion. This sodium-dependent proton secretion could only in part be inhibited by application of 5-(N-methyl-N-isobutyl)-amiloride. Removal of extracellular potassium caused a slow reduction in the rate of acid secretion. A similar reduction was observed in the presence of ouabain, a specific inhibitor of Na(+)-K(+)-adenosinetriphosphatase, and both effects significantly increased with decreasing pH. The results demonstrate a significant pH dependence of the mechanisms of acid release in swim bladder gas gland cells and indicate that sodium-dependent pathways become especially important at low pH.
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C. Prem and B. Pelster Swimbladder gas gland cells cultured on permeable supports regain their characteristic polarity J. Exp. Biol., January 12, 2001; 204(23): 4023 - 4029. [Abstract] [Full Text] [PDF] |
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C. Prem, W. Salvenmoser, J. Wurtz, and B. Pelster Swim bladder gas gland cells produce surfactant: in vivo and in culture Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2000; 279(6): R2336 - R2343. [Abstract] [Full Text] [PDF] |
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