Adaptation to physical exercise increases expression of Ca-ATPase gene in myocardial sarcoplasmic reticulum

Abstract

Gene expression of the key enzyme of the myocardial sarcoplasmic reticulum Ca2+-pump, SERCA-2a isoform was assayed in rats during adaptation to physical exercise (forced swimming). The expression was measured by Northern blot hybridization with subsequent densitometry of the autoradiograms. The signal of mRNA encoding SERCA-2a was referenced to the mRNA signals of marker proteins (S4 and S9 ribosomal proteins, cytoskeletal β-actin and glyceraldehyde-3-phosphate dehydrogenase). The SERCA-2a gene expression gradually increased during adaptation as evidenced by the increased content of SERCA-2a mRNA in particular higher intensity (optical density) of the mRNA signals in autoradiograms. The adaptation-induced increase in the power of the sarcoplasmic reticulum Ca2+-pump can be attributed to activated synthesis and accumulation of SERCA-2a isoform.