Chronic ethanol attenuates centrally-mediated hypotension elicited via alpha-2-adrenergic, but not I1-imidazoline, receptor activation in female rats
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Date
2009-01-16
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Authors
El-Mas, Mahmoud M.
Abdel-Rahman, Abdel A.
Journal Title
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Volume Title
Publisher
East Carolina University
Abstract
Aims—This study dealt with the effect of chronic ethanol administration on hemodynamic responses
elicited by α2-adrenergic (α-methyldopa) or I1-imidazoline (rilmenidine) receptor activation in
telemetered female rats.
Main methods—The effects of α-methyldopa or rilmenidine on blood pressure (BP), heart rate
(HR) and their variability were investigated in rats that received liquid diet without or with ethanol
(5% w/v) for 12 weeks. To evaluate the effect of each drug on cardiovascular autonomic control (BP
and HR variability) in the absence or presence of ethanol, three time-domain indices of hemodynamic
variability were measured: (i) standard deviation of mean arterial pressure (SDMAP), (ii) standard
deviation of beat-to-beat intervals, and (iii) root mean square of successive differences in R-R
intervals.
Key findings—In liquid diet-fed control rats, i.p. rilmenidine (600 μg/kg) or α-methyldopa (100
mg/kg) reduced BP along with decreases and increases, respectively, in HR. Both drugs had no effect
on HR variability but reduced BP variability (SDMAP), suggesting a reduced vasomotor sympathetic
tone. Ethanol feeding attenuated reductions in BP and SDMAP evoked by α-methyldopa but not by
rilmenidine.
Significance—We conclude that chronic ethanol preferentially compromises α2- but not I1-
receptor-mediated hypotension in female rats probably via modulation of vasomotor sympathetic
activity. These findings highlight the adequacy of rilmenidine use to lower BP in hypertensive
alcoholic females.
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Citation
Life Sciences; 84:3-4 p. 111-118
DOI
10.1016/j.lfs.2008.11.006