Iron supplementation in suckling rats: its effect on the heart.

The present study attempted to determine the significance of the "anemia" which normally occurs in infants. We compared various parameters in suckling rats whose hemoglobin concentration had been artificially raised by gastric tube feeding of iron with those of control animals. The 20-day-old experimental animals showed significant increases in the weights of the liver (10%) aan spleen (40%). They had also developed a statistically significant 8% increase in heart weight, accompanied by a smaller myocardial fiber size and, thus, higher fiber density. The association in these young animals of higher than normal hemoglobin levels with smaller hearts and myocardial fibers suggests that the normally developing "anemia" of infancy may well serve an important physiological function: to stimulate myocardial growth.