[Effects of high sodium intake on ventricular remodeling in mice]

Despite extensive research, controversy still exists regarding the role of dietary sodium intake on hypertension and left ventricular (LV) hypertrophy. Echocardiography is a powerful tool to assess LV hypertrophy and recent technical developments allow now its use in small animals.

We examined the effect of high sodium intake on LV geometry using echocardiography in mice. Three groups of Swiss mice 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.

At baseline, heart rate, LV ED septal and posterior wall thicknesses and LV ED diameter were similar between groups. At 8 weeks, for similar heart rate, LV ED posterior wall thickness 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 ass increased in a salt diet dependent manner (0.6%: 0.63 +/- 0.01, 2%: 0.75 +/- 0.01, 4%: 0.80 +/- 0.02 mm, p < 0.01). This increase was correlated with urinary sodium excretion (r = 0.84, p < 0.01) but occurred in the absence of change in arterial pressure (tail-cuff plethysmography; 0.6%: 135 +/- 6.2%: 127 +/- 4 and 4%: 139 +/- 9 mmHg respectively). The in-vivo interventricular septal remodeling was confirmed in perfused fixed preparations of hearts.

Echocardiography allows precise measurements of regional LV wall dimensions in mice, and high sodium intake, in the absence of hypertension, induces interventricular septal remodeling.