Rapid hypotensive response to fasting in spontaneously hypertensive rats

This study examined changes in renal function and mean arterial pressure (M AP) in spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats during 48 h of fasting, independent of changes in sodium intake. Spontaneously hyp ertensive rats (n = 17) and WKY rats (n = 10) were instrumented with artery and vein catheters and sodium intake was clamped at 2.1 mEq/day. By day 2 of fasting, MAP decreased -10 +/- 1 mm Hg (P < .001) in SHR, but did not ch ange significantly in WKY rats. Heart rate decreased significantly in both groups by day 2 of fasting and there was a significant increase in urine vo lume and sodium excretion. Thus, fasting caused a rapid decrease in MAP in SHR that was not due to decreased sodium intake, but may be related, in par t, to volume loss and improved renal excretory function. Am J Hypertens 200 1;14:1123-1127 (C) 2001 American Journal of Hypertension, Ltd.