AJP - Heart and Circulatory Physiology, Vol 233, Issue 3 356-H360, Copyright © 1977 by American Physiological Society
Cardiac cellular responses to altered nutrition in the neonatal rat
M. Hollenberg, N. Honbo and A. J. Samorodin
Rats reared in litters of 18, 12, and 6 to determine whether preweanling
nutritional state would alter rates of cardiac cell division, weighed 31.7,
39.1, 48.2 g, respectively, at 21 days of age. Weights of left ventricles
also increased (93.2, 123.5, and 167.2 mg) as did those of right ventricles
(29.9, 43.2, and 54.3 mg). Total DNA content rose in both ventricles in the
pups reared 6 per litter vs. those reared 18 per litter (6/litter vs.
18/litter), but more so in the left ventricle (79%) than in the right
(24%). Autoradiography confirmed that this increase in ventricular DNA
resulted from increased proliferation of cardiac muscle cells, fibroblasts,
and vascular endothelial cells. When 3H-labeled thymidine was injected on
day 1, autoradiographs prepared on day 21 reflected an increased dilution
of label in the 6/litter rats, consistent with enhanced proliferation. The
labeling index and grains per nucleus of left ventricular muscle cells of
the 6/litter rats were 29% (P less than 0.005) and 20% (P less than 0.001)
less than those of the 18/litter rats. Less vigorous but definite
hyperplasia occurred in the right ventricle, which appeared to respond with
an increase more in cell size than in cell number.
