The Influence of Adrenal and Pituitary Hormones on Liver Arginase Activity Following Nephrectomy or Renal Pedicle Ligation in the Rat *

Impairment of intermediary nitrogen metabolism has been reported in dogs with reduced or abolished kidney function.' In nephrectomized animals fed a high protein diet, the deficiency is manifested by a 65-75%o reduction of urea formation, by an early development of toxic symptoms, and by a short survival time." No explanation is at hand for the influence of renal function on urea formation nor for the observed increase in toxicity. On the basis of reports by Borsook and Dubnoff' and by Cohen and Hayano' concerned with transformation of citrulline into arginine in renal tissue, it was hypothesized that lack of the accessory renal source of arginine might decrease the plasma level of this amino acid and thus influence the urea cycle in the liver. This working hypothesis, as will be reported as part of this paper, has been invalidated by arginine determinations in plasma. Nevertheless, studies on liver arginase activity in rats, 72 hours after bilateral nephrectomy or 24 hours after bilateral ligation of renal pedicles, has demonstrated clearly a significant elevation of the activity of this enzyme.1' Changes in liver arginase activity in normal animals have been previously related to pituitary and adrenal cortical influences. '' It was of interest, therefore, to investigate whether or not hormonal influences are involved in the great rise in liver-arginase activity that follows bilateral nephrectomy or renal ischemia produced by renal pedicle ligation. The paper to be presented includes the results of this investigation.