Genetic isolation of a quantitative trait locus on chromosome 18 associated with blood pressure and salt sensitivity in the SHR

Previous linkage studies in the spontaneously hypertensive rat (SHR) suggested a presence of a major quantitative trait locus (QTL) with effects on blood pressure and salt sensitivity on chromosome 18. To test this hypothesis, we developed an SHR.BN-chromosome 18 (SHR-18) congenic strain by transferring a segment of chromosome 18 between the Adrb2 and Ttr markers from the Brown Norway (BN/Cr) strain onto the SHR/Ola genetic background. The transfer of chromosome 18 segment resulted in a significant decrease in both systolic and diastolic blood pressures and a pronounced resistance to salt in SHR-18 congenic strain which contrasted to a significant increase in blood pressure in the SHR when rats were given 1% salt solution for drinking. After salt loading, the difference in systolic blood pressure achieved nearly 30 mm Hg. Blood pressure decrease in the SHR-18 congenic strain was accompanied by a significantly lower relative heart weights when compared to the SHR. These findings demonstrate that a QTL with major effects on blood pressure and salt sensitivity exists on a differential segment of chromosome 18 trapped within the new SHR congenic strain.