Gene in the Dahl Salt-Sensitive Rat

In the inbred Dahl salt-sensitive rat (SS/Jr strain), it has been proposed that a T for A transversion in the DNA sequence encoding amino acid 276 in the «1 subunit isofonn of Na,K-ATPase may impair ion transport and contribute to the pathogenesis of hypertension. This hypothesis is of major scientific interest because it represents the first attempt to explain the pathogenesis of salt-sensitive hypertension on the basis of a specifically defined mutation at the DNA level. We devised a polymerase chain reaction technique to screen the genomic DNA of multiple SS/Jr rats for the T for A transversion reported in the complementary DNA (cDNA) encoding the ad subunit of Na,K-ATPase. When eight Dahl SS/Jr rats from Harlan Sprague Dawley Inc. were tested with the polymerase chain reaction technique, we found no evidence of this mutation in the Na,K-ATPase gene. Direct sequence analysis of the gene in three SS/Jr rats also did not show the T for A transversion. These results 1) strongly suggest that commercially available Dahl SS/Jr rats do not carry a T for A transversion in the genomic DNA sequence encoding amino acid 276 in the ad subunit isofonn of Na,K-ATPase and 2) raise the possibility that the previous finding of a mutation in the cDNA of the SS/Jr rat may have been due to a reverse transcriptase error during cDNA synthesis. (Hypertension 1991;18:689-693)