Effect of lifelong high or low salt intake on blood pressure, left ventricular mass and plasma insulin in wistar rats.

• Grant number: 06/03739-3
• Support Opportunities: Regular Research Grants - Publications - Scientific article
• Start date: August 01, 2006
• End date: March 31, 2007
• Field of knowledge: Health Sciences - Medicine - Medical Clinics
• Principal Investigator: Joel Claudio Heimann
• Grantee: Joel Claudio Heimann
• Host Institution: Faculdade de Medicina (FM). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Background: Salt restriction is recommended for hypertension treatment in order to reduce blood pressure (BP), but its effect on some risk factors is still a matter of discussion. The aim of this study was to observe the effect of a long period of salt restriction or overload on BP, left ventricular (LVM) and kidney (KM) mass, glucose tolerance and plasma insulin. Methods: Male Wistar rats were fed from weaning with low- (LSD) or high- (HSD) salt diet until 72 weeks of age. After 48 weeks, the diets were changed in half of the rats: HSD until 48 weeks and then LSD (LHSD) and LSD until 48 weeks and then HSD (HLSD). Body weight, BP, electrolyte excretion, creatinine clearance, plasma renin activity, LVM, KM and intravenous glucose tolerance test (ivGTT) with insulin determinations were evaluated. Results: Blood pressure, LVM and KM were higher on HSD than on LSD. Blood pressure was lower on LHSD than on HLSD. There were no differences between LVM and KM on LHSD and HLSD. The relationship between area under the curve (AUC) of insulin and glucose during ivGTT was higher on LSD. No differences were detected between AUC of the two groups of rats whose diet were inverted with 48 weeks of age. Conclusions: Chronic HSD increases BP, LVM and KM and chronic LSD increases plasma insulin in response to a glucose challenge in aging rats. The hypotensive effect of salt restriction is not modified by a previous long period on high salt diet. (AU)