Isolation of a Chromosome 1 Region That Contributes to High Blood Pressure and Salt Sensitivity

Linkage analyses in the spontaneously hypertensive rat (SHR) suggest that a gene involved in blood pressure regulation may be located on rat chromosome 1, in the Sa region. To confirm this possibility, we replaced a region of chromosome 1 in the Wistar-Kyoto rat (WKY) defined by the markers D1Mit3 and MTPA with the corresponding chromosome segment from SHR. Genotyping using 65 polymorphic microsatellite markers throughout the entire genome confirmed the congenic status of this new strain designated WKY. SHR-D1Mit3/Rat57. In male WKY.SHR-D1Mit3/Rat57, mean blood pressures in the daytime and in the nighttime assessed by radiotelemetry were significantly higher than those in male progenitor WKY. Moreover, salt loading significantly increased the mean blood pressure in male WKY.SHR-D1Mit3/Rat57 but not in male progenitor WKY. The present study confirmed the existence of a gene that contributes to high blood pressure and salt sensitivity in this chromosomal segment. This congenic strain represents a new animal model for fine mapping and characterization of the gene in this region involved in salt-sensitive hypertension.