Figure 2.
Dexamethasone has profound anti-apoptotic effects against renal IRI. Apoptosis was studied by (A) TUNEL staining, (B) Western blots for Bcl-xL and Bax expression in whole tissue lysates, and (C) caspase-9 and -3 activity (nmol AMC/min per mg protein, measured using the fluorometric substrate Ac-IETD-AMC and Ac-DEVD-AMC, respectively) in homogenates of kidneys after 24 h of reperfusion. (A) TUNEL staining showed strikingly fewer apoptotic nuclei in rats treated with dexamethasone (I/R+Dex, 3 mg/kg) compared with the control (I/R+V) group. The number of TUNEL-positive cells per high-power field was counted in 5 to 10 fields for each coded slide. Arrows showing TUNEL-stained apoptotic nuclei of the tubular epithelial cells. (B) Dexamethasone prevents the postischemic activation of proapoptotic Bax and significantly increases anti-apoptotic Bcl-xL. Kidneys from sham-operated rats, saline-treated rats (I/R+V), and dexamethasone-treated rats (I/R+Dex, 3 mg/kg, intraperitoneal) were harvested after 24 h of reperfusion. Equal protein loading was confirmed by β-actin. The blots and densitometric quanti-fication are representative of the results obtained from three animals. The same blot was probed for Bcl-xL and Bax, respectively. (C) Dexamethasone pretreatment markedly inhibited the activation of I/R induced caspase-9 and caspase-3 activity, respectively. **P < 0.01, *P < 0.05.