[Characteristics of lengthy spiked tetanus of rat skeletal muscle]

Prolonged unfused tetanuses of the rat m. gastrocnemius were investigated. An increase in the stimulation frequency raised the tension of unfused tetanuses, shortened the time of achievement of the maximum level, and accelerated the beginning of the third (economic) phase. After cooling the muscle to 24-25 degrees C, the unfused tetanuses developed yet during low frequency stimulation and the economic phase began sooner.