Expression of ventricular myosin subunits in the atria of children with congenital heart malformations.

The presence of ventricular myosin light chains in the atria of children with congenital heart disease was demonstrated by two-dimensional polyacrylamide gel electrophoresis, peptide mapping, and Western blot analysis. Ventricular myosin light chains were present in 27% of biopsies from 91 children with different forms of congenital heart disease. Perimembranous ventricular septal defects and tetralogy of Fallot were associated with the presence of ventricular myosin light chains in 50% of patients. The presence of ventricular myosin light chains in these atria did not correlate with pressure or volume overload. Analysis of myosin heavy chain isotype in the same biopsies by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, peptide mapping, and Western blot analysis indicated that there was no detectable expression of ventricular myosin heavy chain (beta-subunit), suggesting that the genes for the myosin heavy chains and light chains are not expressed coordinately.