Without immunosuppression allogeneic kidney transplantation (TX) is followed by an increased urine and solute excretion. We showed that transcriptional down regulation of aquaporins (AQP), solute transporters and regulatory factors could contribute to disturbances of solute and volume maintenance after TX in the rat. Increased renal volume and solute excretion seen under acute rejection is normalized with cyclosporine A (CyA). We used real time PCR to compare the expression of selected transporters after TX with or without CyA. For the majority of the analyzed genes the expression values were slightly higher under CyA compared to TX without CyA. Among other transporters the expression of AQP1 and the Na+/H+ exchanger Type 3 (NHE3) was still down regulated. But the expression of AQP2 and of the epithelial sodium channel (ENaC) was normalized after TX with CyA. The persistent down regulation of AQP1 and NHE3 in the presence of CyA despite an almost normalized renal volume and salt excretion indicates their limited contribution to final renal excretion. Normal expression of key transporters in the collecting duct like AQP2 and ENaC is sufficient to compensate for reduced expression of transporters in the proximal tubule. Supported by the Else-Kröner-Fresenius Foundation.