Excess Sucrose and Glucose Ingestion Acutely Elevate Blood Pressure in Spontaneously Hypertensive Rats

Abstract

Spontaneously hypertensive rats (SHR) were fed 6 different diets. The baseline diet (I) derived equal calories from sucrose, proteins, and fats. Three other diets (II, III, VI) derived the majority of calories from refined CHO, sucrose or glucose, with decreases in calories from proteins or fats. The last two diets (IV, V) were relatively low in sucrose with a higher percentage of the total calories from proteins and fats, respectively. From 3 to 15 weeks on the diets, the highest average BP was in rats consuming high concentrations of sucrose or glucose (II, III, VI). Urinary excretory rates of norepinephrine (NE) at 5, 10 and 15 weeks and epinephrine at 5 and 10 weeks were significantly elevated in rats ingesting diets high in refined CHO, and NE positively correlated with blood pressure (BP) at 5 and 10 weeks of the study. At the end of the study, serum insulin levels were not different, but plasma renin and serum glucagon levels were lower in SHR consuming the diets with high CHO concentrations. We conclude that equally elevated BP are seen with relatively high intakes of either sucrose or glucose, whether the balance of calories is derived from lessening fat or protein. This is secondary, at least in part, to alterations in NE metabolism.

Interplay between Sugar and Salt on Blood Pressure in Spontaneously Hypertensive Rats

“…Salt sensitivity can be bred into animals [14]. Less recognized is that excess sugar consumption also elevates BP [4,7,8,10,15], and sensitivity differs among various strains of rats [5]. In the present investigation, increasing salt to concentrations approximately twice those in regular rat chow elevated SBP relative to that in rats on a diet low in salt content, i.e.. 'h to 'h the usual content.…”

“…1()|. Lack of significant differences in BW also indicates 386 Preuss Sugar, Salt and Blood Pressure that vitamin and mineral ingestion were consistent among the four groups, because diets were formulated to have these elements proportional to calories [ 10]. It is generally accepted that dietary salt ingestion in fluences BP in animals and humans [12].…”

“…All SHR initially con sumed a diet low in sucrose (13% calories) and high in protein (52% calories) with a low salt content (0.14% wt/wt) for roughly 2 months (designated as days-58 to 0). This was the original diet IV described in a previous communication [ 10]. The first group (control) ingested the same diet for the remaining portion of study designated as days 0 to 68. while the diets of the remaining SHRs were changed by altering the salt and/or sucrose-protein proportions: group 2.…”

“…Because of the unusual amounts of sugars consumed by humans, it seems reasonable to assume that lower concentrations of sugar in rat chow should elevate pressure if this is important in age-related BP increases. One possible explanation for lack of response at the 36% sugar level lies in the salt (NaCl) content of the special diets formulated for the earlier work on rats [ 10], To conclusively prove in previous investigations that excess sugars elevated SBP by managing other variables, diets had been designed to be low in Na content, approximately 0 .11 -0.15% weight to weight (wt/wt) compared to the usual 0.30-0.40% wt/wt content. Could addition of more salt influence response of SBP to sugar?…”

Effects of high-sucrose feeding on insulin resistance and hemodynamic responses to insulin in spontaneously hypertensive rats

“…In a previous study, we (35) showed that SHR are insulin resistant and have altered vascular responses to insulin when compared with their normotensive counterpart, the Wistar Kyoto (WKY) rats. Furthermore, high-fructose or high-sucrose diets were reported to further increase blood pressure in those animals (14) and to possibly potentiate the genetic predisposition to insulin resistance (43,49). Therefore, in the light of these previous data, the present study was initiated to further characterize metabolic and vascular dysregulations in response to insulin in SHR and to examine the effect of an environmental factor, that is, a high-carbohydrate diet feeding, on these responses.…”