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 (approximately 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.