Role of nitric oxide synthase (NOS) during ex vivo warm kidney perfusion prior to renal transplantation

Oxygenated hypothermic machine perfusion after static cold storage improves endothelial function of extended criteria donor livers

BACKGROUND

Lack of oxygen and biomechanical stimulation during static cold storage (SCS) of donor livers compromises endothelial cell function. We investigated the effect of end-ischemic oxygenated hypothermic machine perfusion (HMP) on endothelial cell function of extended criteria donor (ECD) livers.

METHODS

Eighteen livers, declined for transplantation, were transported to our center using static cold storage (SCS). After SCS, 6 livers underwent two hours of HMP, and subsequent normothermic machine perfusion (NMP) to assess viability. Twelve control livers underwent NMP immediately after SCS. mRNA expression of transcription factor Krüppel-like-factor 2 (KLF2), endothelial nitric oxide synthase (eNOS), and thrombomodulin (TM) was quantified by RT-PCR. Endothelial cell function and injury were assessed by nitric oxide (NO) production and release of TM into the perfusate.

RESULTS

In HMP livers, mRNA expression of KLF2 (p = 0.043), eNOS (p = 0.028), and TM (p = 0.028) increased significantly during NMP. In parallel, NO levels increased during NMP in HMP livers but not in controls. At the end of NMP cumulative TM release was significantly lower HMP livers, compared to controls (p = 0.028).

CONCLUSION

A short period of two hours oxygenated HMP restores endothelial cell viability after SCS and subsequent normothermic reoxygenation of ECD livers.

Role of combination of L-arginine and α-tocopherol in renal transplantation ischaemia/reperfusion injury: a randomized controlled experimental study in a rat model

What's known on the subject? and What does the study add? Renal ischaemia/reperfusion (I/R) injury is an inevitable consequence of kidney transplantation. It contributes to delayed graft function (DGF), acute renal failure and graft rejection. The present study investigates for the first time the impact of a combination of L-arginine and alpha tocopherol on the renal ischemia/reperfusion injury in a rodent model of kidney transplantation. We found that concomitant administration of L-arginine and α-tocopherol has a more protective effect and synergistic antioxidant effect on ischaemia/reperfusion injury in transplanted rat kidneys.

OBJECTIVES

To investigate the role of L-arginine and α-tocopherol in ischaemia/reperfusion injury in a kidney transplanted rat model.

MATERIALS AND METHODS

In total, 40 male Sprague-Dawley rats subjected to renal transplantation received FK506 (tacrolimus) to overcome early acute rejection episodes. Animals were divided randomly into four groups (ten rats each). Group I were treated with FK506 (2 mg/kg/bw/day) and served as the control group. Group II were treated with L-arginine 300 mg/kg/bw. Group III were treated with α-tocopherol 30 mg/kg/bw. Group IV were treated with L-arginine and α-tocopherol. Urine and blood samples were taken at 0 (before operation), 2, 7 and 14 days post-transplantation for estimation of urine sodium, creatinine, fractional excretion of sodium, serum creatinine, sodium and blood urea nitrogen. Histological examination and measurement of malondialdehyde in kidney tissues were also performed.

RESULTS

Serum creatinine and blood urea nitrogen significantly decreased in L-arginine and α-tocopherol, as well as combination groups, compared to the control group. Malondialdehyde was significantly decreased in the combination group compared to L-arginine and α-tocopherol alone. Histological examination of the control group showed that acute tubular necrosis was markedly decreased in transplanted kidneys treated with a combination of both L-arginine and α-tocopherol.

CONCLUSIONS

Concomitant administration of l-arginine and α-tocopherol has a more protective effect and synergistic antioxidant effect on ischaemia/reperfusion injury in transplanted rat kidneys.

Role of Combined L-Arginine and Prostaglandin E1 in Renal Ischemia-Reperfusion Injury

BACKGROUND

L-Arginine (L-arg) and Prostaglandin E(1) (PGE(1)) have been used effectively as single agents to ameliorate renal ischemia-reperfusion injury. We hypothesized that combined treatment with L-arg and PGE(1 )would be more effective.

MATERIALS AND METHODS

The left renal artery of male Sprague-Dawley rats was clamped for 45 min and the right kidney was removed. Fifty six rats were randomly allocated into 5 groups each consisted of 12 rats except sham group (n = 8). (1) sham, underwent right nephrectomy only; (2) control, untreated ischemic rats; (3) L-arg group, L-arg-treated ischemic rats; (4) PGE(1) group, PGE(1)-treated ischemic rats; (5) L-arg+PGE(1) group, ischemic rats treated with both L-arg and PGE(1). Renal function and histology were assessed on days 2 and 7 postoperatively.

RESULTS

All rats, except control ones, showed a significant improvement of renal function towards normal on postoperative day 7. Serum creatinine and creatinine clearance were significantly better in L-arg+PGE(1) group compared to all other groups on day 7. With the exception of sham-operated and L-arg+PGE(1)-treated animals, all other groups showed significant increases in fractional excretion of sodium (FE(Na)) in response to renal ischemia-reperfusion. The severest tubular damage was determined in the kidneys of control rats. Rats treated with L-arg+PGE(1) had the least severe tubular damage.

CONCLUSION

The administration of either L-arg or PGE(1) attenuates both functional and structural consequences of renal warm ischemia. A near total protection might be achieved when both agents are administered concomitantly.