Moderate Sucrose Ingestion and Blood Pressure in the Rat

Four related hypotheses were tested: 1) substitution of sucrose for starch at moderate levels will significantly elevate blood pressure; 2) most urinary sucrose is endogenous; 3) a change in endogenous sucrose production will alter sodium excretion and blood pressure, and 4) dietary sucrose inhibits endogenous sucrose production. The systolic blood pressures of 25 male rats, 100 days of age, and 25 female rats, 1 year of age, were measured weekly for 8 months. In four experiments, they consumed diets in which 38% of energy came from fat, 15% from protein, 7% from lactose and the remaining 40% from five different sucrose/starch ratios. In experiment 4, a 10% maltose/30% starch diet was fed to one-half the rats fed sucrose in experiment 3. All rats were fed similar amounts of each diet so that there were no significant body weight differences between groups at the end of the 8 months. At periodic intervals all rats were injected with 1 µc of [U-14C]glucose and placed in metabolism cages where a 24 hour urine sample was obtained. Urine was analyzed for sodium, sucrose and sucrose-14C content. Endogenous sucrose production was estimated from the percent of [U-14C]glucose recovered as urine sucrose-14C in 24 hours. All four hypotheses were confirmed.