Abstract
1 . Left and right ventricular hypertrophy were produced by aortic and main pulmonary arterial constriction, respectively, in male rabbits. 2. The measurement of ventricular weight and fiber diameter revealed significant signs of hypertrophy which could be regarded as of physiologic type. 3. Transmembrane resting and action potentials obtained from hypertrophied ventricular muscle cells were not significantly different from, and furthermore, were nearly equal to, that obtained from control cells. 4. An increase in solid angle subtended by hypertrophied cells to the recording electrode was offered as a main voltage increasing factor in ECG, because of the unchanged dipole density on the boundary surface whether muscle cells were hypertrophied or not. 5. The view was proposed that the conduction delay in ventricular hypertrophy is engendered by something other than a mere increase in cell volume.
