[Effect of induced hypotension on damage to renal tubular cells]

Urinary excretion of renal tubular cell enzymes, N-acetyl-beta-D-glucosaminidase (NAG) and gamma-glutamyl transpeptidase (gamma-GTP) was evaluated to elucidate the renal cell damage before, during and after the induced hypotension with trimetaphan (TMP), nitroglycerin (TNG) and prostaglandin E1 (PGE1) under halothane-nitrous oxide-oxygen anesthesia in patients undergoing neurosurgery. Significant increases in excretion of NAG and gamma-GTP were observed in TNG group. Urinary excretion of these two enzymes in TMP group tended to increase, but its increases were not statistically significant. In PGE1 treated group, there was no tendency for urinary NAG excretion, while gamma-GTP excretion tended to decrease compared with that observed before the induced hypotension. Among these three drugs, TNG exerted the most significant effect on urinary excretion of both enzymes and TMP ranked next. Effect of PGE1 on urinary enzyme excretion was weakest. According to the general opinions, degree in stray of renal tubular cell enzyme into urine is thought to parallel with the injury of renal tubular cells. Therefore, the finding obtained in this study suggests that the induced hypotension with PGE1 has a less harmful effect on renal tubular cells.