Studies on the Mechanism of Arrhythmogenic Action of Free Fatty Acids in Blood*
【Supercategory：7. DESCENTE SPORTS SCIENCE Subcategory：7.4 Vol.4】
The cause of sudden death during exercise is one of the urgent problems to be solved in the sports medicine field.
Recently, arrhythmia during exercise is considered as one of the main causes of sudden death and some workers suggest increase of free fatty acids (FFA) in the blood might cause arrhythmia with other factors. Several reports suggest FFA can cause arrhythmia under some pathophysiological conditions and increases of FFA might be one candidate of the arrhythmia. However, the detail of arrhythmogenic mechanisms of FFA have not been fully understood in relation to other non-physiological conditions.
In this study, we conducted following experiments to clarify arrhythmoginic action of FFA. ① effects of FFA on the E-C coupling of the isolated cardiac muscles, ② effects of increase of plasma FFA concentration by heparin or Intralipid injection on the ECG of anesthetized rats, ③ changes of ECG of the man during exercise in the various FFA level. Following results were obtained.
(1) Oleic acid (991, μEq/l) induced prolongation of action potential and diminished the initial rising and plateau phase, and inhibited twitch responses. Spontaneous activity was not observed after application of oleic acid.
(2) Increase of FFA concentration in blood of the rat prolonged P-Q and Q-T interval of the ECG. This suggests FFA inhibits conduction of impulse in conduction system. Arrhythmia was not evoked in spite of very high plasma FFA levels. But the prolongation of action potential cannot completely exclude the possible arrhythmogenic action of FFA, with some other unknown factors.
(3) Rise of FFA levels during exercise in human blood which was obtained from the woman with arrhythmia cannot increase the frequency of arrhythmia generation, and FFA might not be the main factors to generate arrhythmia even though it increased in the blood.
These results were discussed from the viewpoint of possible role of FFA to induce arrhythmia.
DESCENTE SPORTS SCIENCE Vol.5/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
Recently, arrhythmia during exercise is considered as one of the main causes of sudden death and some workers suggest increase of free fatty acids (FFA) in the blood might cause arrhythmia with other factors. Several reports suggest FFA can cause arrhythmia under some pathophysiological conditions and increases of FFA might be one candidate of the arrhythmia. However, the detail of arrhythmogenic mechanisms of FFA have not been fully understood in relation to other non-physiological conditions.
In this study, we conducted following experiments to clarify arrhythmoginic action of FFA. ① effects of FFA on the E-C coupling of the isolated cardiac muscles, ② effects of increase of plasma FFA concentration by heparin or Intralipid injection on the ECG of anesthetized rats, ③ changes of ECG of the man during exercise in the various FFA level. Following results were obtained.
(1) Oleic acid (991, μEq/l) induced prolongation of action potential and diminished the initial rising and plateau phase, and inhibited twitch responses. Spontaneous activity was not observed after application of oleic acid.
(2) Increase of FFA concentration in blood of the rat prolonged P-Q and Q-T interval of the ECG. This suggests FFA inhibits conduction of impulse in conduction system. Arrhythmia was not evoked in spite of very high plasma FFA levels. But the prolongation of action potential cannot completely exclude the possible arrhythmogenic action of FFA, with some other unknown factors.
(3) Rise of FFA levels during exercise in human blood which was obtained from the woman with arrhythmia cannot increase the frequency of arrhythmia generation, and FFA might not be the main factors to generate arrhythmia even though it increased in the blood.
These results were discussed from the viewpoint of possible role of FFA to induce arrhythmia.
DESCENTE SPORTS SCIENCE Vol.5/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
| Researcher | Toshio Sakai*1, Satoshi Kurihara*1, Keizo Kobayashi*2, Masayuki Watanabe*3 |
|---|---|
| University or institution | *1 Department of Physiology, Jikei University School of Medicine, Tokyo, *2 Nurse School of Tokyo Kosei-Nenkin Hospital, *3 Department of Exercise Physiology, Tokyo Gakugei University |
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