Dominant effect of supplemented-sucrose on the low protein diet-induced increase in blood pressure of Sprague-Dawley rats

A low-protein diet (LPD) is known to affect the regulation of hemodynamics, and could contribute to the genesis of hypertension. We investigated the m echanism for the LPD-induced elevation of blood pressure in 52 Sprague-Dawl ey rats. Rats fed the LPD for 8 weeks showed a significantly higher blood p ressure than those fed on a normal-protein diet (NPD) when the LPD included sucrose as a predominant component of carbohydrate (LPD with a high sucros e content, 135 +/- 2 mmHg; NPD, 124 +/- 2 mmHg; p <0.05). However, LPD with a low sucrose content, in which corn starch was the main component of carb ohydrate, did not have a hypertensive effect (125 +/- 2 mmHg). Urinary epin ephrine and norepinephrine excretion was significantly higher in the LPD hi gh-sucrose group than in the NPD and LPD low-sucrose groups, and there was a significant positive correlation between urinary norepinephrine excretion and systolic blood pressure. Urinary nitric oxide excretion was no differe nt between these groups, and 2 % L-arginine administration exerted no antih ypertensive effect on the LPD-induced elevation of blood pressure. Sodium r estriction also did not attenuate the LPD-induced elevation of blood pressu re. These results suggest that the effect of LPD on blood pressure could be interpreted as the effect of the high sucrose content supplemented to the LPD rather than the direct effect of protein restriction, and that the stim ulation of sympathetic nervous activity was associated with this elevation of blood pressure.