The effect of acute ethanol exposure on the chronotropic and inotropic function of the rat right atrium

Consumption of ethanol (CH2CH3OH), both acutely and chronically, is known t o affect cardiac function and may alter the autonomic control of the heart. This study investigated the effects of two modes of acute exposure to etha nol on the chronotropy and inotropy of the rat right atrium with emphasis o n alterations in the adrenergic responses. Atria from rats infused with an anesthetizing level of ethanol for 21 h sho wed a tendency for a greater increase of the unstimulated beating rate with isoproterenol (ISO), while both unstimulated inotropy and the inotropic re sponse to ISO were significantly decreased compared with the control. Right atria in the presence of ethanol in-vitro demonstrated decreased basal act ive tension development and decreased inotropic responses to ISO. No altera tion of the chronotropic response to ISO was evident with any concentration of ethanol. These results demonstrate both an immediate as well as a persistent effect of ethanol on right atrial chronotropy and inotropy. Alterations in the G-s timulatory subunit of the adenylate cyclase system and alterations in myofi lament binding of Ca2+ are consistent with these observed ethanol effects.