Effect of acute exercise and training on metabolism of ceramide in the heart muscle of the rat

Aim: The sphingomyelin signalling pathway operates in the heart muscle. There are no data on the effect of exercise on the functioning of this pathway in the myocardium and it was the aim of the present study to examine this question. Methods: The experiments were carried out on male Wistar rats, 300-320 g of body weight. They were divided into three groups: (1) control, (2) run 3 h on a treadmill moving with a speed of 1200 m h(-1) and set at +10degrees incline, and (3) trained on a treadmill for 6 weeks. The rats were anaesthetized and samples of the left ventricle were taken. They were immediately frozen in liquid nitrogen. Thereafter, lipids were extracted and ceramide and sphingomyelin were isolated by means of thin layer chromatography. Their fatty acids were identified and quantified by means of gas-liquid chromatography. In separate heart samples the activity of neutral, Mg2+-dependent sphingomyelinase and acid sphingomyelinase was determined using labelled sphingomyelin as a substrate. Results: Thirteen different ceramides and sphingomyelins were identified based on their fatty acid residue. Exercise markedly reduced the total content of ceramide-fatty acids and had no effect on the total content of sphingomyelin-fatty acids. Training did not affect the total content either of ceramide-, or sphingomyelin-fatty acids. The activity of both neutral Mg2+-sphingomyelinase and acid sphingomyelinase was reduced after exercise. Training did not affect the activity of neutral sphingomyelinase and reduced the activity of acid sphingomyelinase. Conclusion: It is concluded that acute, prolonged exercise, but not training, markedly affects the operation of the sphingomyelin-signalling pathway in the heart.