Simvastatin and L-arginine preserve renal function after ischemia/reperfusion injury.

BACKGROUND: HMG-CoA reductase inhibitors have been shown to have beneficial renal hemodynamic effects by increasing renal blood flow, independent of their lipid-lowering properties. Currently in organ transplantation, the calcineurin inhibitor cyclosporine A (CyA) is the immunosuppressant of choice. However, its use is limited by its nephrotoxic effects, namely its renal vasoconstrictor properties. The purpose of this study was to determine the effect of an HMG-CoA reductase inhibitor, simvastatin (Zocor), on renal function in rats and on urinary nitrite/nitrate production following ischemia/reperfusion injury (I/R) with concomitant cyclosporine treatment. In addition, L-NAME (N(G)-nitro-L-arginine methyl ester) and L-arginine were administered with CyA to the rats to test the hypothesis that simvastatin's beneficial effects were due to nitric oxide. METHODS: Male Wistar rats (250 g) were anesthetized and the supra-aorta clamped for 40 minutes. The right kidney was removed. After recovery, the rats were divided into five groups: 1) controls, no ischemia, no treatment (CTRL, n = 8); 2) ischemia (ISCH) plus cyclosporine A only (CyA, 5 mg/kg/day i.p., n = 8); 3) ischemia plus CyA and simvastatin (SIM, 10 mg/kg/day, gavage, n = 8); 4) ischemia plus simvastatin plus L-NAME plus CyA (10 mg/kg/day, gavage, n = 8), and 5) ischemia plus simvastatin plus L-arginine (2% in drinking water, n = 7) plus CyA. Five to 7 days after I/R injury, the glomerular filtration rate (GFR) was determined using urinary iohexol clearance. Urinary nitrite/nitrate production was determined using nitrate reductase and the Greiss reaction. Data are expressed as mean +/- SEM, and intergroup comparisons were made using one-way analysis of variance. RESULTS: The GFR values (mL/min) for all five groups are as follows: 1) CTRL = 1.25 +/- 0.10; 2) ISCH plus CyA only = 0.45 +/- 0.06 (P < 0.05 versus CTRL, ISCH only and simvastatin and cyclosporine and simvastatin plus L-arginine and cyclosporine); 3) CyA and SIM = 0.78 +/- 0.09, CyA and L-NAME = 0.62 +/- 0.12, and CyA and L-arginine and SIM = 1.57 +/- 0.12. Results in the control were significantly different from results in the ischemic only and the L-NAME groups (P < 0.05). The L-arginine plus cyclosporine and simvastatin group was significantly higher than the ischemic only group, ischemic plus simvastatin and cyclosporine and the L-NAME plus cyclosporine group (P < 0.05). No significant differences could be detected in the urinary nitric oxide concentrations. CONCLUSIONS: : After I/R injury and cyclosporine treatment, simvastatin and L-arginine preserved renal function, compared with cyclosporine treatment alone, because simvastatin and L-arginine may not have a direct vasoconstrictor effect on the renal microcirculation. They may be suppressing endothelin or increasing other vasodilator mediators such as the vasodilator prostaglandins and/or nitric oxide.

Rapamycin preserves renal function compared with cyclosporine A after ischemia/reperfusion injury.

OBJECTIVES: To determine the effect of cyclosporine and rapamycin administration on renal function after ischemia/reperfusion injury (I/R). Cyclosporine A has known nephrotoxic effects. Thus, cyclosporine therapy subsequent to I/R injury may further exacerbate graft dysfunction. Rapamycin is a newer agent that suppresses the immune system by a different mechanism. METHODS: Male Wistar rats (250 g) were anesthetized, and the suprarenal aorta was clamped for 40 minutes. The right kidney was removed. After recovery, the rats were divided into four groups: group 1, controls, no ischemia and no treatment (n = 10); group 2, ischemia with no treatment (n = 8); group 3, ischemia plus rapamycin (0.17 mg/kg/day gavage, n = 8); and group 4, ischemia plus cyclosporine A (30 mg/kg/day intraperitoneally, n = 9). The glomerular filtration rate was measured 5 to 7 days after I/R injury using urinary iohexol clearance. Data are expressed as the mean +/- SEM, and intergroup comparisons were made using one-way analysis of variance. RESULTS: The mean GFR value for the controls (no ischemia, no treatment) was 1.23 +/- 0.08 mL/min; for group 2 (ischemia, no treatment), it was 1.05 +/- 0.10 mL/min; for group 3 (ischemia plus rapamycin) 1.06 +/- 0.14 mL/min; and for group 4 (ischemia plus cyclosporine A) 0.44 +/- 0.06 mL/min (P <0.05 versus the other three groups). The mean arterial pressure was significantly lower in the ischemic rats treated with cyclosporine A (P <0.05 versus the other three groups). CONCLUSIONS: After I/R injury, rapamycin may preserve renal function compared with cyclosporine treatment, because it does not have a direct vasoconstrictor effect on the renal microcirculation.

Simvastatin attenuates renal ischemia/reperfusion injury in rats administered cyclosporine A.

BACKGROUND: 3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors increase renal blood flow independent of their lipid-lowering properties. In organ transplantation, the calcineurin inhibitor cyclosporine A (CyA) is the immunosuppressant of choice. However, its renal vasoconstrictor properties limit its use. This study aimed to determine the effect of an HMG-CoA reductase inhibitor, simvastatin (Zocor), on renal function in rats after ischemia/reperfusion injury (I/R) with concomitant CyA treatment. METHODS: Male Wistar rats (250 g) were anesthetized and the suprarenal aorta clamped for 40 minutes. The right kidney was removed. After recovery, the rats were divided into 5 groups: (1) control rats, no ischemia, no treatment; (2) ischemia with no treatment; (3) ischemia plus CyA only; (4) ischemia plus CyA and low-dose simvastatin; and (5) ischemia plus CyA and high-dose simvastatin. Five to 7 days after I/R injury, glomerular filtration rate (GFR) was determined using urinary iohexol clearance. RESULTS: The GFR values (mL/min) for all 5 groups were as follows: (1) 1.23 +/- 0.08; (2) 1.05 +/- 0.10; (3) 0.44 +/- 0.06 (P < 0.05 versus groups 1, 2, and 5; one-way analysis of variance); (4) 0.51 +/- 0.04 (P < 0.05 versus groups 1, 2, and 5; one-way analysis of variance); and (5) 0.85 +/- 0.11. CONCLUSIONS: After I/R injury and cyclosporine treatment, simvastatin preserved renal function compared with cyclosporine treatment alone because it may not have a direct vasoconstrictor effect on the renal microcirculation. In fact, it may exhibit vasodilator properties on the renal microcirculation mediated by nitric oxide.