Effects of Exercise on Rat Skeletal Muscle Perfused with Glucose

포도당으로 Perfusion한 쥐의 다리근육에 운동(運勳)이 미치는 영향

Muscular exercise induced by electrical stimulation of femoral nerves in perfused rat hindquarters(5 contractions per sec) in the presence of insulin and glucose effected a rapid increase(c. a. two-fold) in the level of citric acid cycle intermediates. The highest values were found within one minute of stimulation. The tissue concent ratios of lactate, pyruvate and alanine increased rapidly on initiation of exercese. Release of lactate also increased rapidly, whereas that of pyruvate was only moderately elevated. In the course of three minute exercese, the sum of alanine, glutamate and aspartate was only transiently elevated. A fall in creatine-p and ATP in the stimulated muscle was accompanied by increases in tissue level of AMP and release of ammonia into perfusing medium. However, the changes in glutamine were small. It is concluded that the pool of citric acid cycle intermediates is expanded during muscular work due (a) to an elevated level of pyruvate, leading to shifts in the levels of alanine and cycle intermediates vie trans-amination reactions and (b) to stimulation of the purine nucleotide cycle due to elevated AMP, resulting in generation of cycle intermediates and ammonia at the expense of aspartate.

포도당으로 perfusion한 쥐의 뒷다리 근육에 전기자극으로 근육운동을 유도하여 대사물의 농도변화를 측정한 결과는 아래와 같다. 근육내의 구연산회로대사물, 피루빅산, 젖산등의 농도가 상당히 증가하였고 알라닌, 글루타믹산, 아스파틱산등의 아미노산은 약간 증가하였고, 크레아틴 포스페이트, ATP의 농도가 급강하 한데 반하여 AMP와 암모니아의 농도가 증가하였다. 이 결과는 운동시에 에너지대사를 촉진시키는 구연산회로 대사물 일부는 아미노산으로부터 transamination 반응을 통하여 공급되고, 일부는 purine nucleotidecycle반응을 통하여 아스파틱산으로 공급되고 있음을 밝혔다.