Arrhythmogenicity of long-chain fatty acids for cultured rat heart myocytes

Cultures of beating rat heart myocytes were exposed for 1 h to stearic, oleic, linoleic or arachidonic acid (5 x 10(-5) M at a 2 : 1 or 6 : 1 FFA/albumin ratio) in hypoxic or normoxic medium with or without glucose. After the 1 h exposure the medium was changed again to normoxic medium without FFA but with an "equivalent" amount of albumin. The grade of arrhythmia was determined at 0.5, 1, 2, 4, 8 and 16 h after addition of the medium containing FFA. Hypoxia during FFA exposure was not required for arrhythmogenesis although linoleic and arachidonic acids were less and stearic acid was more arrhythmogenic during initial hypoxia than during initial normoxia. Glucose slowed arrhythmogenesis produced by the unsaturated FFA during hypoxia and completely reversed arrhythmogenesis by stearic acid after 16 h with most treatments. Arrhythmogenesis resulting from unsaturated FFA was minimally affected by the FFA/albumin ratios used.