In animal models of conotruncal heart defects, an abnormal calcium sensitivity 
of the contractile apparatus and a depressed L-type calcium current have been 
described. Sarcoplasmic reticulum (SR) Ca(2+) ATPase (SERCA) is a membrane 
protein that catalyzes the ATP-dependent transport of Ca(2+) from the cytosol to 
the SR. The activity of SERCA is inhibited by phospholamban (PLN) and sarcolipin 
(SLN), and all these proteins participate in maintaining the normal 
intracellular calcium handling. Ryanodine receptors (RyRs) are the major SR 
calcium-release channels required for excitation-contraction coupling in 
skeletal and cardiac muscle. Our objective was to evaluate SERCA2a (i.e., the 
SERCA cardiac isoform), PLN, SLN, and RyR2 (i.e., the RyR isoform enriched in 
the heart) gene expression in myocardial tissue of patients affected by 
tetralogy of Fallot (TOF), a conotruncal heart defect. The gene expression of 
target genes was assessed semiquantitatively by RT-PCR using the calsequestrin 
(CASQ, a housekeeping gene) RNA as internal standard in the atrial myocardium of 
23 pediatric patients undergoing surgical correction of TOF, in 10 age-matched 
patients with ventricular septal defect (VSD) and in 13 age-matched children 
with atrial septal defect (ASD). We observed a significantly lower expression of 
PLN and SLN in TOF patients, while there was no difference between the 
expression of SERCA2a and RyR2 in TOF and VSD. These data suggest a complex 
mechanism aimed to enhance the intracellular Ca(2+) reserve in children affected 
by tetralogy of Fallot.