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Assessment of evidence for K+-H+ exchange in isolated type-1 cells of neonatal rat carotid body.
- Source :
- Pflügers Archiv: European Journal of Physiology; Jul1997, Vol. 434 Issue 4, p429-437, 9p
- Publication Year :
- 1997
-
Abstract
- Intracellular pH (pH<subscript>i</subscript>) was measured in enzymically isolated, neonatal rat carotid body type-1 cells, using the fluorophore carboxy-SNARF-1 (AM-loaded), and using the nigericin technique for in situ fluorescence calibration (nigericin is a membrane-soluble K<superscript>+</superscript>-H<superscript>+ </superscript>exchanger). In CO<subscript>2</subscript>/HCO<subscript>3</subscript> <superscript>–</superscript>-free media, inhibiting Na<superscript>+</superscript>-H<superscript>+ </superscript>exchange produced a prompt fall of pH<subscript>i </subscript>(background acid-loading), the rate of which was reduced by raising the extracellular K<superscript>+ </superscript>concentration, [K<superscript>+</superscript>]<subscript>o</subscript>. pH<subscript>i </subscript>recovery from an intracellular acid or alkali load was also sensitive to changes of [K<superscript>+</superscript>]<subscript>o</subscript>. These results are similar to those of Wilding et al. (J Gen Physiol 100:593–608, 1992), who proposed the existence of an acid-loading, K<superscript>+</superscript>-H<superscript>+ </superscript>exchanger (KHE) in the type-1 cell. However, when nigericin was not used for post-experimental calibration, and the superfusion system was flushed exhaustively with strong detergent, alcohol and distilled water, then background acid-loading was attenuated, and the K<superscript>+</superscript> <subscript>o </subscript>sensitivity of pH<subscript>i </subscript>insignificant. Background loading was increased again, and K<superscript>+</superscript> <subscript>o </subscript>sensitivity restored, when cells were monitored in a superfusion system which had previously been exposed to a single nigericin-calibration protocol (followed by a short system wash with strong detergent and distilled water). We conclude that the previously reported expression of KHE in carotid body type-1 cells is an artefact caused by nigericin contamination. We have therefore quantified the pH<subscript>i </subscript>dependence of background loading in uncontaminated type-1 cells. We consider the possible implications of our work for reports of KHE in other cell types. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00316768
- Volume :
- 434
- Issue :
- 4
- Database :
- Complementary Index
- Journal :
- Pflügers Archiv: European Journal of Physiology
- Publication Type :
- Academic Journal
- Accession number :
- 49980569
- Full Text :
- https://doi.org/10.1007/s004240050417