GENOME SCAN AND CONGENIC STRAINS FOR BLOOD-PRESSURE QTL USING DAHL SALT-SENSITIVE RATS

An F-2 population (n = 151) derived from Dahl salt-sensitive (S) and L ewis rats was raised on a 8% NaCl diet for 9 weeks and analyzed for bl ood pressure quantitative trait loci (QTL) by use of a whole genome sc an. Chromosomes 5 and 10 yielded lod scores for linkage to blood press ure that were significant; chromosomes 1, 2, 3, 8, 16, 17, and 18 gave lod scores suggestive for linkage. Chromosome 7 gave a significant si gnal for heart weight with a lesser effect on blood pressure. Congenic strains were constructed by introgressing Lewis low-blood-pressure QT L alleles for chromosomes 1, 5, 10, and 17 into the S genetic backgrou nd. Congenic strains for chromosomes 1, 5, and 10 had significantly lo wer blood pressure than S, proving the existence of QTL on these chrom osomes, but the chromosome 17 congenic strain failed to trap a contras ting QTL allele. The QTL allele increasing blood pressure originated f rom S rats for all QTL except those on chromosomes 2 and 7 in which th e Lewis allele increased blood pressure. Interactions between each QTL and every other locus in the genome scan yielded significant interact ions between chromosomes 10 and 4, and between chromosomes 2 and 3.