Development and characteristics of inbred strains of Dahl salt-sensitive and salt-resistant rats.

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Abstract
Several inbred lines of rats were produced from noninbred stock of Dahl salt-sensitive (S) rats, and several inbred lines were also produced from noninbred stock of Dahl salt-resistant (R) rats. There were significant differences (P < 0.001) in blood pressure response to a high salt diet among the inbred S lines produced, which indicates that the original S stock obtained from Brookhaven Laboratories is not genetically homogeneous. There were no significant differences in blood pressure among the inbred R lines produced. One inbred strain of S and 1 inbred strain of R with the appropriate blood pressure responses were ultimately brother-sister mated for > 20 generations. These inbred strains were called S/JR and R/JR, respectively. Fulminant hypertension and marked vascular and renal lesions developed in the S/JR after 3 to 4 wk on a high salt (8% NaCl) diet, and all S/JR were dead within 8 wk on the high salt diet. In contrast, R/JR survived well on a high salt diet, and hypertension or vascular and renal lesions did not develop. Hypertension and associated vascular and renal lesions developed in S/JR on a low salt diet (0.4% NaCl), but this took 3-4 mo. These characteristics are similar to those originally reported by Dahl for his noninbred, continuously selected stocks. The R/JR were found to have mild hydronephrosis at 4 mo. of age, which probably is genetically determined with which may have been fixed inadvertently in the strain during inbreeding. An age-related, strain-specific polymorphism in a stomach pepsinogen is described in the inbred S/JR and R/JR, which can probably be used as a biochemical marker for the strains.