The effects of arginine deficiency on the water and solute metabolism of weanling rats.

1. Weanling rats fed on a synthetic diet, which was completely deficient in arginine, grew more slowly than rats fed on a similar diet which included arginine.2. No differences in the haemoglobin level or plasma protein concentration or electrophoretic pattern were found in the two groups of rats.3. The arginine-deficient rats drank less water, and excreted less urine, which was more concentrated than that of the control animals, although the solute output was reduced, and the extrarenal water losses were the same.4. The arginine-deficient animals excreted less urea, non-protein nitrogen, creatinine and total solutes. The blood urea concentration of the deficient animals was significantly higher than that of the controls, indicating that arginine deficiency had impaired the excretion of urea.5. There was no difference between the renal weights of both groups of animals when related to total body weight, nor was there a difference in the histological appearance of the kidneys.6. The amounts of arginine vasopression and oxytocin/kg body wt. stored in the neurohypophyses of both arginine-deficient and control animals were the same.