P-159: Detailed mapping of blood pressure QTL on rat chromosome 8

In our previous studies, we demonstrated a significant decrease in blood pressure in a polydactylous SHR.BN-Lx congenic strain when it was compared to the SHR progenitor. The original congenic strain carries a rather long BN-Lx differential segment of chromosome 8. During six cross-intercross cycles, we dissected this long differential segment by recombinations into several sublines and we have found a significant decrease in blood pressure in a SHR.BN-PD4 subline with a limited differential segment spanning the interval between a marker defining the Ncam gene on the centromeric side and a microsatellite marker D8Mit2 on the telomeric side. The length of the recombined differential segment is approximately 5 cM. Recently, we derived a new congenic subline, designated SHR.BN-PD5, with a shorter differential segment defined by markers Lx and D8Got72. For detailed mapping of a limited region of chromosome 8 surrounding the putative blood pressure regulatory QTL, we used a large (SHR x BN-Lx)F2 generation (N[singleapprox]1200). Radiotelemetry measurements of blood pressure in new SHR.BN-PD5 line will enable genetic isolation of responsible QTL in a limited chromosome segment.