DIFFERENCES BETWEEN ATRIAL AND VENTRICULAR PROTEIN PROFILING IN CHILDREN WITH CONGENITAL HEART-DISEASE

The purpose of the present study was to compare protein profiling of a tria and ventricles in children operated for congenital heart disease. Tissue samples were obtained during surgery from patients with normox emic (ventricular and atrial septal defects) and hypoxemic (tetralogy of Fallot) diseases. Protein fractions were isolated by stepwise extra ction from both right ventricular and atrial musculature. The concentr ation of total atrial protein in the normoxemic patients exceeded the ventricular value (110 +/- 2.1 vs 99.9 +/- 4.0 mg.g(-1) wet weight, re spectively); in the hypoxemic group this atrio-ventricular difference disappeared. The concentration of contractile proteins in all cardiac samples was significantly higher in the ventricles as compared with at ria, while the concentration of collagenous proteins was significantly higher in the atria (due to a higher amount of the insoluble collagen ous fraction). The concentration of sarcoplasmic proteins (containing predominantly enzyme systems for aerobic and anaerobic substrate utili zation), however did not differ between ventricles and atria. Furtherm ore, ventricular contractile fractions obtained from both normoxemic a nd hypoxemic patients were contaminated with the myosin light chain of atrial origin. Soluble collagenous fractions (containing newly synthe sized collagenous proteins, predominantly collagen I and III), derived from all ventricular samples, were contaminated by low molecular weig ht fragments (mol. weight 29-35 kDa). The proportion of the soluble co llagenous fraction was significantly higher in atrial but not in ventr icular myocardium of hypoxemic children as compared with the normoxemi c group. It seems, therefore, that lower oxygen saturation affects the synthesis of collagen preferentially in atrial tissue.