Sarcoplasmic reticulum Ca2+ regulatory protein gene expression in human right atrium under hemodynamic overload

Abstract

Sarcoplasmic reticulum (SR) Ca2+-adenosine triphosphatase (ATPase) mRNA expression is reduced in the failing human myocardium. However, it is not known whether SR Ca2+-regulatory protein gene expression is altered in human myocardial tissue subjected to pressure overload or volume overload. We sought to determine whether SR Ca2+-regulatory protein gene expression is altered in human atrial tissue subjected to mechanical overload. We obtained right atrial myocardial tissue (about 250mg) at open-heart surgery from three groups of patients: no hemodynamic overload to the right atrium (control group; 12 patients), atrial septal defect (ASD group; 8 patients), and tricuspid regurgitation (TR group; 7 patients). We measured the myocyte size, the area of interstitial fibrosis, SR Ca2+,-ATPase, and ryanodine receptor mRNA abundance. The isolated cardiocyte area and the percent area of interstitial fibrosis were in the order TR > ASD > control (P < 0.05). The SR Ca2+-ATPase mRNA level in TR was significantly decreased (P = 0.004) compared with the control, whereas in the ASD group it did not differ significantly from control. There were no significant differences in ryanodine receptor mRNA levels among the three groups. SR Ca2+-ATPase gene expression was downregulated in human atrial tissue with TR but not in ASD, which might have resulted from the differences in the degree and/or the type of hemodynamic overload to the myocardium.

Pulmonary artery banding alters the expression of Ca2+transport proteins in the right atrium in rabbits

“…Previous studies have demonstrated that mRNA levels of Serca2a in the atria are decreased by mechanical stress (33,38), which is consistent with data from many studies investigating the change in Secra2a transcripts in the pressure or volume-overloaded ventricles (10,23,26,42). Also, Bauer et al (7) demonstrated that, in the pig ventricle, in a similar model, mRNA levels of Serca decrease and mRNA levels of atrial natriuretic factor (ANF) increase.…”