Regional myocyte size in compensated right ventricular hypertrophy in the ferret.

The effect of pressure-induced right ventricular hypertrophy on regional myocyte size and shape and regional myocardial wet weight was studied by comparing 20 ferrets which underwent pulmonary artery banding at a weanling age to 19 non-operated siblings. Using isolated myocyte preparations from six myocardial regions in 10 banded and seven non-banded ferrets, a 60% increase in cell volume in the right ventricular outflow tract and the right ventricular free wall was shown to be due primarily to an increased cross-sectional area of individual myocytes. The right side of the interventricular septum exhibited an intermediate increase in cell volume, while the left side of the interventricular septum did not respond to the pulmonary artery banding procedure. These findings confirm that localized hemodynamic changes produce hypertrophy of individual myocytes in selected regions of the heart and that a pressure-induced model of hypertrophy involves an increased cross-sectional area of myocytes, with minimal change in cell length.