Estimation of the Cell Number of Heart Muscle in Experimental Cardiac Hypertrophy

The total numbers of heart muscle cells and of interstitial cells were estimated in the Goldblatt rats by a histometrical method. The thickness of muscle fibers and the length of muscle cells were also estimated. The heart weight and heart muscle volume increased significantly in the hypertensive group. The total number of heart muscle cells was 30-54 millions in the hypertensive group, while it was 25-38 millions in the control group. The total number of interstitial cells was 88-102 millions in the hypertensive group and 72-87 millions in the control group. There was a significant increase of both cells in the hypertensive group. Both the total number of heart muscle cells and that of interstitial cells were proportional to the heart muscle volume. There were no significant differences in the thickness of muscle fibers and in the length of muscle cells between the two groups. It was concluded that the heart weight and heart muscle volume increased in the hypertensive group, and the increase in heart muscle volume was due to an increase in the cell number. Hyperplasia of the muscle cells rather than their hypertrophy was regarded as the major process underlying cardiac hypertrophy.