Radiotelemetric Evaluation of Hemodynamic Effects of Long-Term Ethanol in Spontaneously Hypertensive and Wistar-Kyoto Rats1

Abstract

This study determined the hemodynamic effects of chronic ethanol in telemetered freely moving age-matched spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. Changes in blood pressure (BP), heart rate (HR), and plasma norepinephrine (as index of sympathetic activity) were evaluated in pair-fed rats receiving liquid diet with or without ethanol (5%, w/v) for 12 weeks. The SHRs exhibited higher baseline BP and lower HR compared with WKY rats. When normalized for body weight, daily ethanol intake was higher in SHRs compared with WKY rats. However, blood ethanol concentration was similar except for a higher level in SHRs at weeks 7 through 9. Ethanol had no effect on BP in WKY rats but caused decreases in BP in SHRs that reached a maximum (∼30 mm Hg) at week 5 and remained thereafter. Ethanol also caused reductions in the BP variability and the circadian fluctuations in BP in SHRs but not in WKY rats. Plasma norepinephrine levels were elevated by ethanol in WKY rats, but not in SHRs. The HR was not affected by ethanol in SHRs and showed increases in WKY rats. These findings suggest that chronic ethanol feeding differentially affects BP in SHRs (hypotension) and WKY rats (no effect). The lack of a hypotensive response to ethanol in WKY rats may relate, at least partly, to the associated sympathoexcitation. The present study used the telemetry technique for BP measurement, which eliminates the confounding and stressful effects of other conventional techniques.