CARDIOVASCULAR HYPERTROPHY DOES NOT PREDISPOSE TO GENETIC-HYPERTENSION

It has been proposed that cardiovascular hypertrophy precedes and cont ributes to the development of genetic hypertension. In a genetically s egregating population we determined whether susceptibility to high blo od pressure was associated with cardiovascular structural abnormalitie s in youth. In 9-week old male F2 rats derived from a cross of spontan eously hypertensive rats (SHR) and inbred normotensive Donryu (DRY) ra ts we determined left ventricular mass (LVM) by echocardiography and t he media-lumen ratio (MLR) of mesenteric resistance vessels by biopsy. Direct mean arterial pressure was measured in the same rats at 20 wee ks of age. The ranges of LVM and MLR in young F2 rats encompassed valu es seen SHR and DRY at this age. However, no correlation was observed between LVM or MLR and subsequent blood pressures at 20 weeks of age. The blood pressure of F2 rats with cardiovascular structural phenotype s within the SHR range was no higher than the remainder of the F2 popu lation. These studies do not support the hypothesis that hypertrophy o f the heart or mesenteric resistance vessels confer susceptibility to the development of genetic hypertension.