Kidney cross transplants in Dahl salt-sensitive and salt-resistant rats

Previous kidney cross-transplant studies have demonstrated that the genotype of the kidney plays a role in determining the blood pressure of the recipient in Dahl salt-sensitive (S) and salt-resistant (R) rats. The present studies were designed to elucidate this role. Kidney cross transplants were performed in unilaterally nephrectomized male recipients (John Rapp strains), such that each rat had a native kidney and a transplanted kidney of the opposite genotype. S and R rats with a native kidney and a transplanted kidney of the same genotype served as controls. After 4 wk on a 7.8% NaCl diet, rats were anesthetized and renal clearance studies were performed. S kidneys had lower glomerular filtration rate (GFR) and renal plasma flow (RPF) than R kidneys, and these differences were determined by the kidney's genotype rather than the recipient's, since S kidneys in R recipients tended to have lower GFR and RPF than R kidneys in S recipients. In contrast, independent of the kidney's genotype, the kidneys in S rats tended to have higher fractional excretion of H2O and Na (FEH2O and FENa) than the kidneys in R rats. Thus there were genetically determined differences in renal function between S and R rats; some (RPF and GFR) were intrinsic to the kidney, whereas others (FEH2O and FENa) were intrinsic to the host.(ABSTRACT TRUNCATED AT 250 WORDS)