EFFECTS OF HIGH SODIUM-INTAKE ON VENTRICULAR REMODELING IN MICE

Background. Despite extensive research, controversy still exists regar ding the role of dietary sodium intake on hypertension and left ventri cular (LV) hypertrophy. Echocardiography is a powerful tool to assess LV hypertrophy and recent technical developments allow now its use in small animals. Methods, We examined the effect of high sodium intake o n LV geometry using echocardiography in mice. Three groups of Swiss mi ce were submitted, for 8 weeks, to different salt diets (0.6, 2 and 4 % NaCl; n = 12, n = 8 and n = 12 respectively); LV end-diastolic (ED) septal and posterior wall thicknesses, LV ED diameter were measured at baseline, 4 and 8 weeks. Results. At baseline, heart rate, LV ED sept al and posterior wall thicknesses and LV ED diameter were similar betw een groups. At 8 weeks, for similar heart rate, LV ED posterior wall t hickness were not different (0.6 %: 0.64 +/- 0.01, 2 %: 0.62 +/- 0.08 and 4 %: 0.67 +/- 0.03 mm respectively) but LV septal wall thickness a ss increased in a salt diet dependent manner (0.6 %: 0.83 +/- 0.01, 2 %: 0.75 +/- 0.01, 4 %: 0.80 +/- 0.02 mm, p <0.01). This increase was c orrelated with urinary sodium excretion (r = 0.84, p <0.01) but occure d in the absence of change in arterial pressure (tail-cuff plethysmogr aphy: 0.6 %: 135 +/- 6, 2 %: 127 +/- 4 and 4 %: 139 +/- 9 mmHg respect ively). The in-vivo interventricular septal remodeling was confirmed i n perfused fixed preparations of hearts. Conclusion. Echocardiography allows precise measurements of regional LV wall dimensions in mice, an d high sodium intake, in the absence of hypertension, induces interven tricular septal remodeling.