Palmer W K
Department of Physical Education, University of Illinois, Chicago 60680.
Med Sci Sports Exerc. 1988 Dec;20(6):525-30.
The effect of one bout of intense swimming caused significant increases in the cyclic AMP content of fast-twitch white skeletal muscle, liver, and heart. Further investigation of the exercise-induced increase in myocardial cyclic AMP indicates that the nucleotide content remained elevated long after (24 h) termination of exercise. This increase in cyclic AMP was time dependent, with the level increasing gradually throughout the work bout. The increase in cardiac cyclic AMP seemed to be independent of work intensity, provided that work time was of sufficient duration (greater than or equal to 30 min). Increases in cardiac cyclic AMP were also seen when rats were exposed to 2 degrees C for 1-7 d. The increases in cyclic AMP seen following exercise and cold exposure were accompanied by an increase in cardiac cyclic AMP phosphodiesterase (PDE) activity. Our working hypothesis was that prolonged elevations in cyclic AMP produced an induction and/or activation of one or more of the PDE isozymes. When we administered dibutyryl cyclic AMP to rats, cardiac PDE activity was increased. This increase was inhibited by cycloheximide, suggesting that the elevated enzyme activity is mediated by the synthesis of new protein. These data support the concept that cyclic AMP is involved in the regulation of its own metabolism during physiological stress.
一次剧烈游泳运动可使快肌白骨骼肌、肝脏和心脏中的环磷酸腺苷（cAMP）含量显著增加。对运动诱导心肌cAMP增加的进一步研究表明，在运动终止后很长时间（24小时），核苷酸含量仍保持升高。cAMP的这种增加呈时间依赖性，在整个运动过程中水平逐渐升高。心脏cAMP的增加似乎与运动强度无关，只要运动时间足够长（大于或等于30分钟）。当大鼠暴露于2℃环境1 - 7天时，也可观察到心脏cAMP增加。运动和冷暴露后cAMP的增加伴随着心脏环磷酸腺苷磷酸二酯酶（PDE）活性的增加。我们的工作假设是，cAMP的长期升高会诱导和/或激活一种或多种PDE同工酶。当我们给大鼠注射二丁酰环磷酸腺苷时，心脏PDE活性增加。这种增加被放线菌酮抑制，表明酶活性的升高是由新蛋白质的合成介导的。这些数据支持了cAMP在生理应激期间参与自身代谢调节的概念。
