Polyploidy in cardiac myocytes of normal and hypertrophic human hearts; range of values.

Two-wavelength scanning DNA cytophotometry was used for DNA and protein estimation in human ventricular myocytes. In many hypertrophic hearts weighing more than 500 g the DNA content assessed by ploidy of myocytes, was within the range of normal adult variation (4-10c, where c is the haploid DNA content). A correlation was found between the protein content of myocytes and the weight of the hypertrophic ventricle. In congenital heart disease, the excessive polyploidy (up to 15-20c) developed through the normal route of myocyte polyploidization in childhood. Excessive polyploidization was revealed only in overloaded hypertrophied ventricles. A correlation was identified between the ploidy level, the ventricular weight and age of the child. Excessive polyploidy was also detected in adults with congenital or acquired in childhood diseases. There was no correlation between the myocyte ploidy and age. We propose that childhood polyploidy excess persists in these adults. The ranges of polyploidy are compared with the recent data on genome: protein ratio in cardiac myocytes and the interrelationships allow us to discuss the significance of childhood heart polyploidy as a reserve utilised under pathological conditions in adults.