Analysis of molecular heterogeneity of Dahl/Iwai salt-sensitive rats and salt-resistant rats

Molecular evidence, using DNA fingerprint analyses, of extensive genetic heterogeneity between spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) and even within some of the WKY colonies has been reported. Thus we investigated the genetic relations between Dahl S and R rats newly inbred by Dr. Iwai. Genomic DNA was isolated from the liver of four Dahl S and four Dahl R rats, digested with the restriction enzyme HinfI or AluI, and separated in 1.2% agarose gel by electrophoresis. Then, DNA fingerprinting was performed by Southern blot analysis using the human myoglobin 33.6 minisatellite probe. Bands were detected in an alkaline phosphatase reaction system. Within the same strains, there was no heterogeneity of these fingerprinting patterns. The S and R rats shared 82% of the bands in the HinfI-digested DNA and 93% of those in the AluI-digested DNA. These shared values were much greater than the reported value (54%) between SHR and WKY from Charles River Laboratories. These newly inbred Dahl S and R rats may be appropriate, although still limited, experimental animals for investigating the pathophysiology of salt-sensitive hypertension.