Relationship between baroreceptor reflex function and end-organ damage in spontaneously hypertensive rats

The purpose of this study was to further illustrate the relationship betwee n baroreceptor reflex sensitivity (BRS) and hypertensive end-organ damage ( EOD) and to test the hypothesis that impairment of BRS aggravates EOD in hy pertension. We studied baroreflex-mediated changes in heart rate [expressed as baroreceptor sensitivity to heart rate control (BRSHR)] and blood press ure [expressed as baroreceptor sensitivity to blood pressure control (BRSBP )] in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) tha t were used as controls, both at the age of 50-52 wb. Rats were also instru mented to record BP, HR, and BP variability (BPV) in the conscious, unrestr ained state. In SHR compared with WKY, BP and BPV were significantly increa sed, whereas BRSHR and BRSBP were significantly decreased. SHR had remarkab le EOD when compared with WKY (EOD score: 6.3 +/- 2.5 vs. 2.9 +/- 0.8, P < 0.01). Univariate regressive analysis demonstrated that EOD score was incre ased with BP and BPV and decreased with BRS. In multivariate analysis, EOD score was predicted by greater systolic BP and lower BRS and HR variability . These results indicate that BRS is negatively related to BW and EOD score , and impaired BRS might be one of the major causes for hypertensive EOD.