Alleles of the spontaneously hypertensive rat decrease blood pressure at loci on chromosomes 4 and 13

In this study the spontaneously hypertensive rat (SHR/Mol) and the spontaneously diabetic BB/OK rat were crossed, and the Fl hybrids were backcrossed onto the BB/OK rat in order to search for cosegregation between blood pressure and loci on chromosomes 4 and 13. Cosegregation of microsatellites on chromosomes 4 (Spr, Npy, D4mit6, Il-6) and 13 (Atp1a2, D13Mit1, D13Uwm1) with blood pressure was evaluated using one-way analysis of variance. On chromosome 4 linkage of the Npy and D4Mit6 markers to systolic blood pressure was observed. A blood pressure QTL was also found on chromosome 13 within the renin locus. Surprisingly, alleles of the SHR strain at loci showing linkage to blood pressure on chromosome 4 and 13 promote lower blood pressure than the same alleles from the BB/OK strain. The transfer of D4Mit6 and renin locus from the SHR rat onto the genetic background of BB/OK rat will probably not lead to a model of diabetic hypertension, but the thorough characterisation of such congenics could contribute to the explanation of genetics and pathophysiology of hypertension in the SHR rat. (C) 1997 Academic Press.