The Depressant Effect of Fatty Acids on the Isolated Rabbit Heart

The toxic effects of stearic and oleic acids on the rabbit myocardium were investigated in a plasma-free system using a modified Langendorf isolated heart preparation. A 0.1% stearic acid or 0.1% oleic acid solution was added to the solution which perfused the coronary vessels. The coronary flow, and the rate and amplitude of contractions progressively deteriorated until there was death of the heart. Equimolar albumin incubated with the fatty acid solutions prevented this toxic effect. The time of incubation was important to the blocking of toxicity for stearic acid but not for oleic acid. No incubation period was required to prevent the toxicity of the oleic acid when combined with albumin. This suggested a difference in the rate of albumin-fatty acid binding for different fatty acids. Unbound fatty acids, saturated or unsaturated, were extremely toxic to the heart.