Cardiac hypertrophy and performance of Dahl hypertensive rats on graded salt diets.

• DOI: 10.1161/01.hyp.6.4.475
• Publication Date: 2012-06-12T00:22:33Z
• Authors: M A Pfeffer; J Pfeffer; I Mirsky; J Iwai
• Keywords: 0301 basic medicine; Heart Ventricles; Blood Pressure; Cardiomegaly; Rats, Inbred Strains; Stroke Volume; Organ Size; Sodium Chloride; Diet; Rats; 03 medical and health sciences; Hypertension; Animals; Female; Cardiac Output

The relationship between arterial pressure and left ventricular (LV) functional capacity and LV mass during the natural development of cardiac hypertrophy was assessed in Dahl-resistant (R) and -sensitive (S) hypertensive rats maintained on three dietary NaCl regimens (0.4%, 4.0%, and 8.0% for 9 weeks, then 4.0%) from 5 until 20 weeks of age. In R rats, arterial pressure and LV mass were unaffected by diet. In contrast, S rats demonstrated levels of arterial pressure and LV hypertrophy that were graded according to dietary NaCl. Hemodynamic studies on rats under ether anesthesia demonstrated that the graded pressure elevation in S rats was produced by corresponding increases in total peripheral resistance, as cardiac output did not vary. During acute volume loading, the S rats on all diets achieved the same maximum stroke volume as did R rats, despite the marked increase in the arterial pressure of S rats. An analysis of the ejection fraction/afterload relationship demonstrated preserved contractile state. The ability of the left ventricle to generate pressure was increased in S rats in direct proportion to the degree of LV hypertrophy. Thus, in young adult S rats, cardiac performance was well compensated since pump and contractile functions were maintained and pressure-generating capacity was increased in relation to the degree of LV hypertrophy.