Delayed Example in Rigor Mortis of Spinal Cord Destroyed Plaice Detected by Measurements of Isotonic Contraction and Isometric Tension

Abstract

In spinal cord destroyed plaice, two types of ATP degradation pattern were observed. The delay type in rigor of spinal cord destroyed plaice showed slow development of rigor contraction along with an early rapid decrease of ATP concentration, and fast development of rigor contraction along with a slight decrease of ATP concentration near the ultimate ATP/IMP ratio. The initial ATP/IMP ratio was higher and the decrease of the ratio was slower. In addition, the ATP/IMP ratio at the inflection point between slow and fast rigor developments was rather higher. As a result, the rigor development in contraction and tension was delayed. The acceleration type commenced strong rigor contraction when the ATP/IMP ratio was still high. This rigor mortis developed together with tetanus (i.e. rapid ATP degradation by the leak of calcium ions). The onset of rigor mortis was early and its development was rapid. Since the acceleration type fish transmitted the strong impulse of spinal cord destruction to the sarcoplasmic reticulum some time after death, the leak of calcium ions occurred some time after death. The acceleration type was similar to the stressed fish in the fast attainment of rigor contraction, but the onset of rigor contraction was 2 h later in the acceleration type than in the stressed fish. Since the stressed fish died with excessive exercise applied forcibly, the leak of calcium ions occurred at 2 h after death.