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 funct ion 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 concentrati ons of ethanol (1, 2, 3, and 4% vol/vol) showed dose dependent decreas es in developed pressure and the systolic peak and overall amplitude o f the Indo 1 fluorescence transients (=[Ca2+]i), that were partially a ntagonised by high extracellular Ca2+ ([Ca2+]o=4 mM). The ethanol conc entrations 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 etha nol 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 fluoresc ence and developed pressure was fitted to a single sigmoid curve irres pective of [Ca2+]o. During ethanol washout, there was a dose dependent overshoot of the fluorescence ratio. Conclusions: Only high concentra tions of ethanol depressed left ventricular function in a dose depende nt manner by decreasing the amplitude of [Ca2+]i transients. High [Ca2 +]o partially antagonised acute alcoholic cardiac depression by increa sing the amplitude of [Ca2+]i transients. [Ca2+]i is a mediator of the acute cardiac effects of ethanol in perfused intact rat hearts.