Studies on the Mechanism of Arrhythmogenic Action of Free Fatty Acids in Blood (II)
【Supercategory：7. DESCENTE SPORTS SCIENCE Subcategory：7.5 Vol.5】
Many reports have appeared on the relationship between the increase of blood free fatty acids (FFA) and the occurrence of arrhythmia since Oliver pointed out it. In these reports, there are few evidence that FFA could be the cause of sudden death in untrained person during exercise and arrhythmia in the trained person. This is an urgent important problem in physical fitness research, in parallel with the relation between blood FFA concentration and acute myocardial infarction.
In the animal experiments, these are several reports that FFA could cause arrhythmia in normal heart. On the other hand, no effects of FFA even on the heart under the pathological condition have been suggested. We have already reported that the rapid increase of blood FFA concentration up to 3.5 mEq/l did not cause arrhythmia in the anesthetized rat. However, the detailed analysis of ECG showed that the prolongation of P-R and Q-T intervals and blood FFA had an inhibitory action on the excitation conduction in the conducting systems. In addition to it, we indicated the specific inhibitory effects of oleic acid on the excitation-contraction coupling mechanism of the guinea-pig ventricular muscle.
In the present study, we intended to do experiments on the following subjects.
(1) Which part of the conducting system is specifically inhibited by the increase of blood FFA level in anesthetized rat?
(2) Relationship between the inhibition of conducting system and FFA concentration in the solution in isolated perfusing heart preparation, of the guinea-pig.
(3) Effects of FFA on the pacemaker potentials of the isolated S-A node of the rabbit with microelectrode method.
Following results were obtained.
(1) A rise in blood FFA level caused the prolongation of P-R interval in ECG record which might be due to the atrial and/or A-V conduction delay.
(2) In the excised guinea-pig heart, oleic acid inhibited A-V conduction and caused A-V block depending on the concentration of oleic acid.
(3) In the S-A node preparation of the rabbit, oleic acid changed the rhythm of spontaneous electrical activities, and especially diastolic depolarization phase was influenced.
(4) The cellular mechanism of the effect of oleic acid on the S-A and A-V nodal cells was discussed.
DESCENTE SPORTS SCIENCE Vol.5/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
In the animal experiments, these are several reports that FFA could cause arrhythmia in normal heart. On the other hand, no effects of FFA even on the heart under the pathological condition have been suggested. We have already reported that the rapid increase of blood FFA concentration up to 3.5 mEq/l did not cause arrhythmia in the anesthetized rat. However, the detailed analysis of ECG showed that the prolongation of P-R and Q-T intervals and blood FFA had an inhibitory action on the excitation conduction in the conducting systems. In addition to it, we indicated the specific inhibitory effects of oleic acid on the excitation-contraction coupling mechanism of the guinea-pig ventricular muscle.
In the present study, we intended to do experiments on the following subjects.
(1) Which part of the conducting system is specifically inhibited by the increase of blood FFA level in anesthetized rat?
(2) Relationship between the inhibition of conducting system and FFA concentration in the solution in isolated perfusing heart preparation, of the guinea-pig.
(3) Effects of FFA on the pacemaker potentials of the isolated S-A node of the rabbit with microelectrode method.
Following results were obtained.
(1) A rise in blood FFA level caused the prolongation of P-R interval in ECG record which might be due to the atrial and/or A-V conduction delay.
(2) In the excised guinea-pig heart, oleic acid inhibited A-V conduction and caused A-V block depending on the concentration of oleic acid.
(3) In the S-A node preparation of the rabbit, oleic acid changed the rhythm of spontaneous electrical activities, and especially diastolic depolarization phase was influenced.
(4) The cellular mechanism of the effect of oleic acid on the S-A and A-V nodal cells was discussed.
DESCENTE SPORTS SCIENCE Vol.5/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
| Researcher | Toshio Sakai*1, Satoshi Kurihara*1, Yosuke Matsune*1, Keizo Kobayashi*2, Masayuki Watanabe*3 |
|---|---|
| University or institution | *1 Department of Physiology, Jikei University School of Medicine, *2 Nurse School of Tokyo Kosei-Nenkin Hospital, *3 Department of Exercise Physiology, Tokyo Gakugei University |
Keywords
blood free fatty acids (FFA), arrhythmia, sudden death, myocardial infarction