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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 less than 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 one inbred strain of R with the appropriate blood pressure responses were ultimately brother-sister mated for more than 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 weeks on a high salt (8% NaCl) diet, and all S/JR were dead within 8 weeks 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 to 4 months. 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 months of age, which probably is genetically determined and which may have been fixed inadvertently in the strain during inbreeding.(ABSTRACT TRUNCATED AT 250 WORDS)
Rapp et al. (Wed,) studied this question.