[Changes in functional and metabolic characteristics of isolated rat heart during initial phase and long lasting...

Mechanical performance, tissue content of high-energy phosphates (ATP and CP), glycogen and phosphorylase activity were measured in isolated rat hearts either just after excision (hearts arrested by plunging in ice-cold perfusate) or during long time perfusions (6 h) at 37 degrees C. Arrested hearts exhibited : (1) higher total phosphorylase activity (a + b); (2) higher percentage of phosphorylase a; (3) lower CP content. During perfusion, high energy phosphates appeared well maintained whereas glycogen content and phosphorylase activity decreased with a significant correlation between these two parameters. The validity of this isolated heart model and possible implications of the variations in phosphorylase activity are discussed.