Objective: The salt-sensitive Dahl rat and the spontaneously hypertensive rat develop comparable spontaneous hypertension on a low-salt diet, whereas only the salt-sensitive Dahl rat strain develops a striking increase in blood pressure and cardiovascular hypertrophy on a high-salt diet. We set out to identify quantitative trait loci (QTLs) contributing to the progression of salt-induced organ damage in hypertension by studying an F2 population derived from both strains.
Methods and results: We determined systolic blood pressure (SBP), vascular aortic hypertrophy (AH), cardiac left ventricular (LV) hypertrophy (LVH), and LV fibrosis in 230 male F2-animals on a high-salt diet. A strong correlation between AH and LVH was found (r=0.58, P<0.0001), and genome-wide QTL mapping detected suggestive or significant QTLs in overlapping chromosomal fragments for AH and LVH on chromosomes 1, 3, and 19, respectively. A significant influence of SBP on the extent of LVH and AH was evident at all QTLs, although significant linkage to SBP (together with LVH) was only found on chromosome 9. No QTLs for LV fibrosis were detected.
Conclusions: This study demonstrates a strong correlation between AH and LVH in salt-sensitive hypertension and identifies QTLs contributing to the progression of cardiovascular hypertrophy in this condition.