ACUTE EFFECTS OF ETHANOL ON CARDIAC-FUNCTION AND INTRACELLULAR CALCIUM IN PERFUSED RAT-HEART

Objective: The aim was to evaluate effects of ethanol on cardiac function and intracellular Ca2+ ([Ca2+]i) in perfused rat hearts. Methods: A Langendorff perfused rat heart preparation was used. Changes in [Ca2+]i) were evaluated by surface fluorometry in hearts loaded with Indo I-AM. Results: Clinically relevant concentrations of ethanol (0.2 or 0.4% vol/vol) had no significant haemodynamic effects. High concentrations of ethanol (1, 2, 3, and 4% vol/vol) showed dose dependent decreases in developed pressure and the systolic peak and overall amplitude of the Indo 1 fluorescence transients (=[Ca2+]i), that were partially antagonised by high extracellular Ca2+ ([Ca2+]o=4 mM). The ethanol concentrations that decreased developed pressure by 50% were 1.4 and 2.6% in the low (1.5 mM) and high [Ca2+]o, respectively. Four per cent ethanol decreased the amplitude of Indo 1 fluorescence transients to 54.5(SD 3. 1) and 64.6(7.9)% of control values in the low and high [Ca2+]o, respectively. A relationship between the amplitude of Indo 1 fluorescence and developed pressure was fitted to a single sigmoid curve irrespective of [Ca2+]o. During ethanol washout, there was a dose dependent overshoot of the fluorescence ratio. Conclusions: Only high concentrations of ethanol depressed left ventricular function in a dose dependent manner by decreasing the amplitude of [Ca2+]i transients. High [Ca2+]o partially antagonised acute alcoholic cardiac depression by increasing the amplitude of [Ca2+]i transients. [Ca2+]i is a mediator of the acute cardiac effects of ethanol in perfused intact rat hearts.