Response of High Protein Diets and Unilateral Nephrectomy During Reproduction in the Rat. ∗

This study was undertaken to determine the extent to which the task of excretion of nitrogenous katabolites could be intensified in the organism by simultaneous reduction of kidney tissue, reproduction with lactation and high protein intake and to observe the physiological adjustments made to these conditions. Unilateral nephrectomy was performed on adult female rats which were placed immediately on the experimental rations and, as soon as the regular oestrous cycle was reestablished, were mated. The weight of the litters at birth and at weaning were compared and lactation closely observed during this time. Some of the mother rats were killed after the first litter was weaned and others were bred one or more times further, and then killed.

Reproduction on the protein diets was fairly successful but lactation was definitely deficient until certain changes were made in the experimental food. In Table I is given a summary of the high protein rations and control low protein rations fed.

Renal enlargement calculated on the basis of increase in weight of the remaining (left) kidney over the “normal” kidney weight corresponding to the actual heart weight ranged from 219 to 29% in the animals on the protein-rich rations and from 58 to 7% in those on the low-protein control food. The degree of renal enlargement appeared to be due largely to 2 factors, namely, to the concentration of dietary protein and to the extent to which the maternal organism was called upon to satisfy the nutritional demands of the suckling young. The length of time on the ration after nephrectomy, the age of the animal, and gestation unaccompanied by lactation, were comparatively negligible factors in the renal enlargement under the conditions of these experiments.