Ca 2+/H + exchange via the plasma membrane Ca 2+ ATPase in skeletal muscle

J. Desantiago, Daniel Batlle, M. Khilnani, S. Dedhia, J. Kulczyk, R. Duque, J. Ruiz, C. Pena-Rasgado, Hector Rasgado-Flores*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The aims of this work were to determine: 1) whether Ca 2+ exit via the plasmalemmal Ca 2+ ATPase (PMCA) is coupled to H + entry via a Ca 2+/H + exchange; 2) whether operation of PMCA has an absolute requirement on external H + (H o); and 3) the stoichiometry and voltagedependence of the Ca 2+/H + exchange. Barnacle muscle cells were used because of the ease with which they can be internally-perfused (e.g., with 45Ca), voltage-clamped and impaled with a pH electrode. Thus, the simultaneous measurement of plasmalemmal Ca 2+ and H + fluxes can be measured. The effects of H o, intracellular ATP, PMCA blockers, and membrane potential (V M) were studied on PMCA-mediated Ca 2+/H + exchange. The results indicate that: i) Ca 2+ efflux is promoted by external acidification, is accompanied by a membrane depolarization, and by an intracellular acidification greater than the one resulting from H o "leak" and PMCA-mediated ATP hydrolysis; ii) H o-dependent Ca 2+ efflux is inhibited by PMCA blockers and by ATP depletion and is accelerated by membrane depolarization (∼3 fold by 20 mV depolarization); iii) the coupling ratio of the Ca 2+/H + exchange depends on Ho: at an extracellular pH (pH o)=6.5, the ratio is 1Ca 2+:∼3H +; at pH o=8.2, Ca 2+ efflux rate is 3 times slower and the ratio is 1Ca 2+:<1H +.

Original languageEnglish (US)
Pages (from-to)4641-4660
Number of pages20
JournalFrontiers in Bioscience
Volume12
Issue number12
DOIs
StatePublished - May 1 2007

Keywords

  • Acidosis
  • Ca /H exchange
  • Ca ATPase
  • Ca buffering
  • PH
  • PMCA

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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