Effects of interstrain renal transplantation on NaCl-induced hypertension in Dahl rats

Previous studies using renal transplantation suggested that the genotype of a homograft kidney plays the primary role in determining chronic arterial pressure levels in Dahl salt-sensitive (DS) and salt-resistant (DR) rats, but this conclusion derived largely from observations during low NaCl diet. Recent studies indicate that extrarenal factors, including the sympathetic nervous system, play a critical role in the development of NaCl-induced hypertension in DS rats. To assess the contribution of extrarenal and renal factors in the development of NaCl-induced hypertension in Dahl rats, we performed renal transplantation in DS and DR rats. Both kidneys of the recipient were removed at the time of transplantation. Four groups of rats (n = 18-23 in each group) were fed a high NaCl (8.0%) diet for 2 weeks after renal transplantation. These included DRR, DRS, DSR, and DSS, where DR or DS indicates the recipient strain and the subscript indicates the homograft strain. Mean arterial pressure was measured from the femoral artery in conscious rats. On a high NaCl diet, mean arterial pressure was significantly lower (p less than 0.05) in DRR (103 +/- 2 mm Hg; mean +/- SEM) compared with DRS (145 +/- 5 mm Hg), DSR (151 +/- 7 mm Hg), and DSS (160 +/- 5 mm Hg). The finding that DR rats with a DS kidney (DRS) developed hypertension during high NaCl diet confirms the concept that the kidney plays an important hypertensinogenic role in the Dahl strain. The fact that DS rats with a DR kidney (DSR) also developed hypertension indicates that extrarenal factors also contribute significantly to NaCl-induced hypertension in DS rats.