EFFECTS OF HIGH SUGAR DIETS ON RENAL FLUID, ELECTROLYTE AND MINERAL HANDLING IN RATS - RELATIONSHIP TO BLOOD-PRESSURE

Objective: We examined whether sugar-induced systolic blood pressure ( SBP) elevations in rats may develop, in part, through a mechanism comm on to salt-induced hypertension, i.e., renal retention of water and sa lt. Design: Spontaneously hypertensive rats (SHR) ate four diets: two high (>50% of calories) and two low (<12% of calories) in sugar (sucro se). SBP, various urinary parameters, and the renal angiotensin and pr ostaglandin systems were assessed. Results: SHR consuming diets high i n sugar showed significantly decreased urinary volume and excretion of electrolytes, which coincided with increasing SBP. When low sugar die ts replaced high sugar diets, SBP and urinary parameters rapidly retur ned to baseline. SHR received captopril while consuming high sugar die ts, and both SBP and urinary parameters assumed baseline values, compa rable to ones seen in SHR consuming low sugar diets. A direct angioten sin II receptor antagonist (DuPont 753) did not influence SBP. However , we found decreased PGE2 excretion in SHR consuming excess sugar. Con clusions: Salt and water retention occur early during sugar-induced hy pertension due to reduced renal excretion, consistent with some part i n the pathogenesis. The effects of high sugar diets on SBP were not du e to angiotensin II inhibition, however, decreased availability of vas odilatory prostaglandins may play a role in the renal events and sugar -induced hypertension in SHR.