Abstract
Acetaldehyde (CH3CHO), a major metabolite of ethanol, has been postulated to be an indirect-acting sympathomimetic agent. This hypothesis was tested in vitro on the electrically driven left atria of guinea pigs. Simultaneous recordings of transmembrane potentials and isometric contractions were made. CH3CHO (0.1-30 mM) induced a dose-related biphasic response in the contractile force of the atrium. Low concentrations (0.3-3 mM) induced positive inotropic responses, whereas high concentrations (10-30 mM) induced negative inotropic responses and arrhythmias. Pretreatment with reserpine inhibited the positive inotropic effects induced by CH3CHO without altering the negative inotropic responses. Propranolol inhibited all inotropic responses induced by CH3CHO. Low concentrations of CH3CHO induced changes in the action potential similar to those seen with norepinephrine or tyramine. it was concluded that CH3CHO induced positive inotropic responses through indirect sympathetic mechanisms and a depression through a direct effect on myocardial tissue.
Footnotes
- Received October 10, 1968.
- Accepted January 22, 1969.
- © 1969, by The Williams & Wilkins Company
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