Sympathetic and Renin-Angiotensin Systems Contribute to Increased Blood Pressure in Sucrose-Fed Rats

Abstract

BACKGROUND: This study evaluated the effect of chronic sucrose feeding on hemodynamic parameters and renal sympathetic nervous activity. In addition, angiotensin I, II, and 1-7 levels were determined in plasma, heart, kidney, and the epididymal adipose tissue. METHODS: Male Wistar rats were treated for 30 days with 20% sucrose solution (n = 21) or tap water (n = 19) and food ad libitum. Blood pressure, cardiac output, and total peripheral resistance were recorded at the end of the 30-day treatment period. Sympathetic and angiotensinergic systems were evaluated by acute hexamethonium and captopril administration; plasma and tissue (heart, kidney, and epididymal adipose tissue) angiotensins were measured by high-performance liquid chromatography; and angiotensin-converting enzyme activity was determined by continuous fluorescent assay. Plasma renin activity and plasma levels of insulin and leptin were evaluated by radioimmunoassay. RESULTS: Chronic sucrose feeding was associated with increased blood pressure (BP) (129 +/- 1 v 102 +/- 3 mm Hg) and circulating insulin (171%) and leptin (356%) levels when compared with the control group. The sucrose group also showed a 27% higher renal sympathetic nervous activity. The depressor response to hexamethonium was similar in both groups, whereas captopril caused a more pronounced decrease in BP in the sucrose group than in controls (-40 +/- 2 v -11 +/- 2 mm Hg), possibly reflecting the higher plasma renin activity and plasma content of angiotensin II and renal angiotensin II in sucrose rats. CONCLUSIONS: These findings suggest a specific renal renin-angiotensin-sympathetic activation as a potential mechanism for the cardiovascular changes in response to chronic sucrose feeding.