Cardiovascular Research Advance Access [Accepted Manuscript] published online on October 22, 2008
Cardiovascular Research, doi:10.1093/cvr/cvn285
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Sarcolemmal Ca2+-ATPase ability to transport Ca2+ gradually diminishes after myocardial infarction in the rat
Maczewski1
1 Department of Clinical Physiology, Postgraduate Medical School, Warsaw, Poland
2 Cardiovascular Research Group, University of Manchester, Manchester, UK
3 Department of Immunology, Center of Biostructure Research, Medical University of Warsaw, Warsaw, Poland
Corresponding author: Urszula Mackiewicz, PhD, Department of Physiology, Postgraduate Medical School, Marymoncka Str 99/101, 01-813 Warsaw, Poland, Tel.: 48 225693840, Fax: 48 225693712, E-mil address: urszulam{at}cmkp.edu.pl
AIM: Plasmalemmal Ca2+-ATPase (PMCA) is involved in Ca2+ handling and the regulation of intracellular signaling pathways in the heart. However, there is no information on its functioning in heart hypertrophy and failure. We aimed to investigate the Ca2+ transporting ability of PMCA, Na+/Ca2+ exchanger (NCX) and sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA2a), as well as the amplitude of Ca2+ transients and cell shortening in myocytes isolated from rat hearts at various time intervals after myocardial infarction (MI).
METHODS: The rate of Ca2+ transport by PMCA, NCX and SERCA2a was estimated from the rate constants of decay of electrically and caffeine-evoked Ca2+ transients in left ventricular myocytes isolated 1 week, 1 month and 3 months after MI.
RESULTS: One week, 1 month and 3 months after MI the PMCA transporting function decreased by 27%, 41%, and 67%, respectively, compared to that in time-matched sham animals. This was accompanied by increased amplitude of Ca2+ transients, cell shortening and SR Ca2+ content. Carboxyeosin, a blocker of PMCA, increased the amplitude of shortening in cells extracted from control hearts. This effect was absent 1 and 3 months after MI. PMCA1, 2 and 4 mRNA was unchanged in the ventricular muscle 3 months after MI as compared to time-matched sham animals. The NCX transporting function was increased by 65% only 3 months after MI, while SERCA2a transporting function was decreased by about 18% at all three time points after MI.
CONCLUSION: The ability of PMCA to transport Ca2+ progressively decreases over 3 months after MI. This decrease may contribute to the increase of amplitude of Ca2+ transients and myocyte shortening.
Time for primary review: 28 Days