THE PROBABLE DAMAGE OF THE RENAL PROXIMAL TUBULAR CELLS DURING EXTRACORPOREAL CIRCULATION IN VIEW OF THE EXCRETION OF URINARY ENZYMES

Renal function and damage during extracorporeal circulation (ECC) were studied in 20 patients (adult: 11, child: 9) who were scheduled for elective open heart surgery. The excretion of urinary γ-glutamyl transpeptidase (γ-GTP) and N-acetyl-β-D-glucosaminidase (NAG), which were mainly located in the renal proximal tubular cells, were measured with creatinine clearance (Ccr), free water clearance (CH2O), and fractional excretion of sodium (FENa). In adult group, Ccr decreased by about 30% during and after ECC compared with before ECC, and the excretion of urinary γ-GTP and NAG increased about 2.5 and 10 times respectively. The former was correlated with urinary flow rate, but the latter was not. FENa also increased. The excretion of these enzymes and FENa gradually decreased, but the higher values were remained in intensive care unit. In child group, the change of these parameters were also similar with those in adult group. These results suggest that the probable damage of the renal proximal tubular cells happen with impaired renal function during ECC.