Alteration of Renal Natriuretic Systems Is Associated with the Development of Hypertension and Precedes the Presence of Renal Damage in a Model of Metabolic Syndrome

Abstract

Objective: The aim of this study was to determine the presence of alterations in the natriuretic systems of atrial natriuretic peptide and renal dopamine in a model of metabolic syndrome induced by fructose overload and to associate them with changes in systolic blood pressure, renal function, Na+/K+-ATPase status and microalbuminuria. Methods: Male Sprague-Dawley rats were divided into control (C) and fructose (F) groups receiving drinking water or a fructose solution (10% W/V), respectively, for 4, 8 and 12 weeks. L-dopa and dopamine, sodium, creatinine and albumin were measured in urine and ANP, insulin, sodium and creatinine in plasma. Systolic blood pressure was measured by indirect method and the renal activity and expression of Na+/K+-ATPase as well as the renal expression of A- and C-type natriuretic peptide receptors were assessed. Results: Fructose overload was associated with a significant increase in insulinemia and systolic blood pressure levels and a decrease in urinary sodium excretion since week 4. A significant increase in L-dopa excretion and a decrease in dopamine excretion (increased urinary L-dopa/dopamine ratio) due to fructose overload were observed since week 4 with a decrease in plasma atrial natriuretic peptide at weeks 8 and 12. These changes were accompanied by increased activity and expression of Na+/ K+-ATPase, decreased A-type natriuretic peptide receptor and increased C-type natriuretic peptide receptor expression. Microalbuminuria was observed at week 12 of fructose overload. 1