Renal Expression of Dahl SS/Jr (S) and Congenic Rats after 28 days of dietary salt elevation

The overlap of congenic regions in an earlier substitution mapping study suggested the location of two blood pressure quantitative trait loci (QTL)-containing regions in the q-terminus of rat chromosome 3, QTL1 and the more distal, QTL2. Male SS/jr rats and two congenic substrain rats S.R(D3Mco36-D3Mco46) and S.R(D3Mco36-D3Got166) were maintained on a low salt (0.4% NaCl Harlan Teklad diet TD7034) diet until 39-41 days of age and then fed an intermediate (2% NaCl Harlan Teklad diet TD94217) salt diet for 28 days. These 3 rat strains will be hereafter referred to as S, S.R(ET3x1), and S.R(ET3x2), respectively. Both congenic substrains carry SR/jr (R)-rat alleles for QTL2 on an S-rat genetic background, while S.R(ET3x2) also carries R-rat alleles for QTL1. Renal gene expression analysis was used to identify differentially expressed genes or genes with altered activity within the S.R(ET3x2) congenic region. Keywords: strain differences in response to dietary changes Rats of each strain were divided into 4 groups: S, n=2 rats/group; S.R(ET3x1), n=3 rats/group; and S.R(ET3x2), n=3 rats/group. Equal amounts of left kidney RNA from each rat in a group were pooled, such that four different pools of kidney RNA (biological replicates) were prepared for each of the three rat strains. Total RNA was isolated from the kidneys of each rat separately. Gene expression data were analyzed from Affymetrix Rat RAE230 A and B GeneChips.