BLOOD-PRESSURE RESPONSES TO SUCROSE INGESTION IN 4 RAT STRAINS

Among four strains examined, spontaneously hypertensive rats (SHR) show a marked (20 mm Hg, P < .01) systolic blood pressure elevation (SBP), Sprague-Dawley (SD) and Wistar-Kyoto (WKY) rats developed a moderate elevation (8 mm Hg, P < .01), and a normotensive Wistar rat (WAM) had a lesser SBP elevation (6 mm Hg, P = NS) after excess sucrose ingestion. The SBP elevations found in SHR were noted at 2 and 4 weeks after starting the dietary treatments. Corresponding with SBP changes, plasma renin activity (PRA), aldosterone, and neuropeptide Y (NPY) concentrations all decreased with the high sucrose-low protein diet compared to the low sucrose-high protein diet, while circulating insulin levels were unchanged. Although norepinephrine (NE) and epinephrine (E) excretion tended to be higher in the rats eating the high sucrose-low protein food, the differences were not statistically significant. The differences in these parameters could influence the SBP in SHR, SD, and WKY, but virtually similar qualitative and quantitative blood and urinary findings were found in WAM, a strain of rat that showed no significantly increased SBP. Removing one kidney increases the CHO-induced SBP response of WKY to levels comparable to those seen in SHR, converting a moderate responder to a highly sensitive one. We conclude that under well-controlled conditions there are obvious differences in the SBP response to the macronutrients in the diets of various rat strains and that SHR possess some intrinsic mechanism(s), most likely associated with renal metabolism, which make this strain more sensitive to refined CHO-induced SBP elevations.