Previous studies have shown that introgression of Brown Norway (BN) chromosome 13 containing the BN allele of the renin gene into the Dahl saltsensitive (SS) genetic background (SS.13BN consomic rats) not only restores normal regulation of plasma renin activity and circulating ANG II levels, but also restores vasodilator responses to low PO2 and acetylcholine (ACh). Although SS.13BN rats are 98% identical to SS rats genetically, chromosome 13 contains a number of genes in addition to the renin allele that could affect vascular relaxation mechanisms. The goal of the present study was to evaluate the dilator responses of middle cerebral arteries (MCA) to low PO-2, ACh, and the stable prostacyclin analogue iloprost in SS-derived congenic rat strains receiving smaller portions of BN chromosome 13 surrounding the renin allele. This study utilized congenic strains 7, 8, and 9 containing successively smaller portions of BN chromosome 13, but all carrying the BN renin allele. All rats were fed low salt (0.4% NaCl) diet. MCA of SS rats failed to dilate, whereas MCA of all 3 congenic strains dilated in response to low PO2, ACh, and iloprost, supporting the hypothesis that replacement of the SS renin gene with the BN renin allele rescues vascular relaxation that is lost in SS rats.

Fundamental medical sciences