Angiotensin converting enzyme activity in compensatory renal hypertrophy.

Serum and tissue (kidney's) angiotensin-converting enzyme (ACE) activity has been examined in Wistar rats (10 males and 10 females), seven days after unilateral nephrectomy. Renal hypertrophy was determined by measurement of kidney absolute mass. Serum and tissue ACE activity was determined by spectrophotometric method using hippuryl-l-histidyl-l-leucine (Hip-His-Leu) as a substrate. The ACE serum activity was expressed in units that correspond to 1 nmol of hippuric acid released by enzymatic hydrolysis of Hip-His-Leu substrate per minute/ml serum. The ACE tissue activity was expressed in units that correspond to 1 nmol of hippuric acid released by enzymatic hydrolysis of Hip-His-Leu substrate per minute/mg protein or mg kidney's tissue. The ACE serum activity significantly increased (p<0,05) seven days after unilateral nephrectomy. The ACE tissue activity, expressed in units that corresponds to 1 nmol of hippuric acid released by hydrolysis of Hip-His-Leu substrate per minute/mg protein, was higher seven days after unilateral nephrectomy then in kidney control, but the difference was not significant compared to the values determined in kidney control. The ACE tissue activity, expressed in units that correspond to 1 nmol of hippuric acid released by hydrolysis of Hip-His-Leu substrate per minute/mg tissue, was increased seven days after unilateral nephrectomy, which is statistically significant compared to the activity of the same enzyme in kidney control (p<0,01). The results indicate that ACE, probably has an important role in development of adaptive compensatory mechanisms after unilateral nephrectomy.