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Ethanol exhibits alpha receptor blocking-like properties in anesthetized rats
R D Russ1, A A Abdel-Rahman, W R Wooles
1Department of Pharmacology, School of Medicine, East Carolina University, Greenville, North Carolina 27858.
Summary
Ethanol exhibits alpha receptor blocking activity by reducing pressor responsiveness to adrenergic agents. This effect is similar to known alpha blockers and does not impact angiotensin II-induced responses, indicating specific vascular action.
Area of Science:
- Pharmacology
- Cardiovascular Physiology
Background:
- Ethanol's cardiovascular effects are complex and not fully understood.
- Alpha-adrenergic receptors play a critical role in regulating blood pressure.
Purpose of the Study:
- To investigate the effect of ethanol on alpha-adrenergic receptor-mediated pressor responsiveness in vivo.
- To determine if ethanol possesses alpha receptor blocking activity.
Main Methods:
- Rats were anesthetized and instrumented for blood pressure measurement.
- Dose-response curves for phenylephrine and norepinephrine were constructed before and after ethanol administration.
- Responses to angiotensin II were assessed to rule out nonspecific vascular effects.
Main Results:
- Ethanol administration resulted in a partial blockade of alpha receptor-mediated pressor responses to phenylephrine and norepinephrine.
- This blockade was comparable to that induced by yohimbine and prazosin.
- Ethanol did not affect angiotensin II-induced pressor responses, suggesting specific alpha receptor interaction.
Conclusions:
- Ethanol demonstrates alpha receptor blocking-like activity in vivo.
- The findings suggest a specific mechanism for ethanol's influence on vascular tone.
- Ethanol's cardiovascular effects may involve direct modulation of adrenergic signaling pathways.