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 to affect cardiac function and may alter the autonomic control of the heart. This study investigated the effects of two modes of acute exposure to ethanol on the chronotropy and inotropy of the rat right atrium with emphasis on alterations in the adrenergic responses. Atria from rats infused with an anesthetizing level of ethanol for 21 h showed a tendency for a greater increase of the unstimulated beating rate with isoproterenol (ISO), while both unstimulated inotropy and the inotropic response to ISO were significantly decreased compared with the control. Right atria in the presence of ethanol in-vitro demonstrated decreased basal active tension development and decreased inotropic responses to ISO. No alteration 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-stimulatory subunit of the adenylate cyclase system and alterations in myofilament binding of Ca2+ are consistent with these observed ethanol effects.