THE METABOLISM OF AMINO ACIDS AND PROTEIN IN THE ADRENALECTOMIZEDNEPHRECTOMIZED RAT1

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Abstract
The rates of urea formation in nephrectomized and adrenalectomized-nephrectomized rats previously on low K diets were investigated as measures of N metabolism. Studies were conducted at 18 and 40 hrs. postoperatively. The adrenalectomized-nephrectomized animals formed urea at the same rate as did the controls during the first 21 hrs. postoperatively but generally at a lower rate after 40 hrs. The adrenalectomized-nephrectomized rats formed urea at the same rate after an injn. of amino acids as did the control nephrectomized rats. The adrenalectomized-nephrec-tomized rats showed no increase in urea formation after injn. of rat plasma, but did if adrenal cortical extract was given 2 and 3 hrs. before the plasma. The control nephrectomized rats responded to intraven. plasma injn. by a significant increase in urea formation. The latter was prevented if glucose was given with the plasma. Glucose intraven. had no effect on the rates of urea formation in either group of rats at 18 hrs. postoperatively. At 40 hrs. postoperatively it caused a significant decrease in urea formation in the nephrectomized rats with intact adrenals. The data are interpreted to support the view that the action of the adrenal cortex in protein metabolism is at the level of protein breakdown itself rather than at the level of deamination of amino acids, regardless of whether this be a direct or an indirect action of the hormone.