Administration of cyclosporin A (CsA) may induce cholestasis, and this effect has been attributed to impaired hepatocellular uptake, transport, secretion and intestinal absorption of bile acids. Disturbances of the enterohepatic circulation may affect metabolism of bile acids. To test whether liver transplantation and treatment with CsA alters pool sizes or synthesis and turnover rates, we determined kinetics of primary bile acids in patients after orthotopic liver transplantation on CsA. Two male and four female patients were studied 6-20 months after transplantation. They had no overt signs of cholestasis, graft dysfunction or rejection. Kinetics of cholic acid (CA) and chenodeoxycholic acid (CDCA) were simultaneously determined after oral administration of [24-13C]-CA and [24-13C]-CDCA on the basis of isotope dilution in a single pool of bile acids. Ten healthy volunteers served as controls. After orthotopic liver transplantation, pool sizes, fractional turnover rates and synthesis rates of both primary bile acids, CA and CDCA were not significantly different from control subjects. In spite of the known interference of CsA with the enterohepatic circulation of bile acids, in the majority of patients after orthotopic liver transplantation without cholestasis, graft dysfunction of rejection, treatment with CsA does not disturb kinetics of primary bile acids.
Ischemia–reperfusion injury (IRI) remains a key component of graft damage during transplantation. Erythropoietin (EPO) induces anti-inflammatory and anti-apoptotic effects via the EPOR2/βcR2 complex, with a potential risk of thrombosis. Previous work indicates that EPO has EPOR2/βcR2-independent protective effects via direct effects on the endothelium. As the EPOR2/βcR2 receptor has a very low affinity for EPO, we aimed to test the hypothesis that EPO doses below the level that stimulate this receptor elicit cytoprotective effects via endothelial stimulation in a porcine liver transplantation model. Landrace pigs underwent allogenic liver transplantation (follow-up: 6 h) with a portojugular shunt. Animals were divided into two groups: donor and recipient treatment with low-dose EPO (65 IU/kg) or vehicle, administered 6 h before cold perfusion and 30 min after warm reperfusion. Fourteen of 17 animals (82.4%) fulfilled the inclusion criteria. No differences were noted in operative values between the groups including hemoglobin, cold or warm ischemic time. EPO-treated animals showed a significantly lower histopathology score, reduced apoptosis, oxidative stress, and most important a significant up-regulation of endothelial nitric oxide (NO) synthase (eNOS). Donor and recipient treatment with low-dose EPO reduces the hepatic IRI via EPOR2/βcR2-independent cytoprotective mechanisms and represents a clinically applicable way to reduce IRI.
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