Combining distinctive and novel loci doubles BP reduction, reverses diastolic dysfunction and mitigates LV hypertrophy

Abstract

Diastolic dysfunction often represents the onset of diastolic heart failure (DHF). We previously showed in principle that diastolic function in Dahl salt-sensitive rats (DSS) can be genetically determined by quantitative trait loci (QTLs) that also modulate blood pressure (BP). We analyzed cardiac phenotypes of four 'single' congenic strains by echocardiography, in which a specific DSS chromosome segment was replaced by its normotensive Lewis homologue. Two of the strains permanently lowered BP, and but attenuated diastolic dysfunction only in rats at 10 weeks of age, not at 15 weeks fed on a 2% NaCl diet starting from 8 weeks of age. We then combined multiple QTLs by integrating several 'single' congenic strains. As a result, BP was greatly reduced. Cardiac dysfunction and LV hypertrophy were continuously improved from 10 to 15 weeks, although the degree and timing of the improvement varied among different congenic combinations. Distinct QTLs exist that simultaneously modulate BP and diastolic function. These QTLs, in combination, synergistically lowered BP and permanently alleviated or reversed diastolic dysfunction. The genes that are contained in the congenic strains affecting diastolic function are not known for their specific influence on BP. Novel long-term strategies of prognosis, diagnosis and therapy for hypertensive DHF appear from this work.