Failure of alleles at the Na+, K +-ATPase ??1 locus to cosegregate with blood pressure in Dahl rats

A previously described Pst I restriction fragment length polymorphism in Dahl rats at the Na+, K(+)-adenosine 5'-triphosphatase (ATPase) alpha 1 isoform locus was tested for cosegregation with blood pressure in segregating populations. Inbred Dahl salt-sensitive (S) and inbred Dahl salt-resistant (R) rats were crossed to produce F1 rats, and three segregating populations, F1 x R, F2 and F1 x S, were produced and raised on a high-salt diet for variable periods to attain the maximal blood pressure response in each population. In no segregating population was there a significant difference in blood pressure among genotypes at the Na+, K(+)-ATPase alpha 1 locus. Power calculations suggest that single-allele dosage effects of less than 7.5 mmHg were unlikely to be detected. It is concluded that either the S and R alleles at the Na+, K(+)-ATPase alpha 1 locus do not influence blood pressure under the conditions of these experiments (high dietary salt, Dahl rat genetic background) or, if they do, their effect is small.