Ethanol Discontinuation Does Not Fully Reverse Its Chronic Effects on Blood Pressure, Heart Rate, and Their Variability in SHRs: Diurnally‐Unrelated Effects

Abstract

Chronic ethanol alters diurnal hemodynamic and autonomic rhythms in SHRs, but not in, Wistar‐Kyoto rats (WKY). In this study, we investigated if these effects of ethanol could be reversed following ethanol withdrawal. Telemetered SHRs and WKY rats were fed a liquid diet containing 5% w/v ethanol or isocaloric diet for 12 weeks, after which ethanol diet was replaced by control diet for another 2 weeks. Blood pressure (BP), heart rate (HR), hemodynamic variability, and their circadian rhythms were monitored during the last week of ethanol regimen and after withdrawal. Compared to little effects in WKYs, ethanol‐treated SHRs exhibited significant increases in HR and decreases in BP and time‐domain variability of mean arterial pressure (SDMAP) and HR (standard deviation of R‐R intervals, SDRR, and root mean square of successive R‐R differences, rMSSD). Ethanol discontinuation fully and partially reversed the cardiac and hypotensive responses, respectively, but had no effect on the SDMAP reductions caused by ethanol. Unlike WKYs, SHRs showed no diurnal variations in BP or rMSSD, and reversed HR and SDMAP rhythms. The defective diurnal profiles in SHRs continued during ethanol treatment. Further, the hemodynamic profiles following ethanol discontinuation were similar during light and dark cycles. Overall, ethanol discontinuation reverses the cardiac, but not BP, responses in a diurnally independent manner.