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To understand the mechanism in postmortem autolysis better, processes in the postmortem degradation of myofibril proteins in the presence of protease inhibitors were studied. Male Wistar rats were given injections of the carboxyl-, thiol-, and serine-protease inhibitors, pepstatin, Ep-475[L-transepoxysuccinyl-leucylamide(3-methyl) butane; E-64-C], and chymostatin, via the femoral vein. Control rats were similarly treated with saline. Then, myofibril proteins were isolated from their cardiac and femoral muscles and from those of control animals at various times after death, and degradation of these myofibril proteins with time was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In cardiac muscle, alpha-actinin was degraded rapidly, followed by the heavy chain of myosin and light chain of myosin (L2). Actin and the light chain of myosin (L1) were degraded slowly. the degradations of the heavy chain of myosin, alpha-actinin, tropomyosin and L2 after 14 days were not inhibited by pepstatin, but were inhibited by Ep-475 and chymostatin. In skeletal muscle, L1 and L2 were degraded rapidly, followed by the heavy chain of myosin and alpha-actinin. Actin was degraded slowly and was still unchanged 2 weeks after death. The degradations of protein components were inhibited by pepstatin, Ep-475 and chymostatin. These results indicated that after death the components of myofibrils are degraded by various proteases at various rates depending on their properties or structures. This degradation is fundamentally the same in cardiac and skeletal muscles, but inhibitors have somewhat different effects on the postmortem degradation processes after death in the two types of muscle.

In rats, fibrinolytic activity and acidosis increased rapidly after death. Postmortem fibrinolysis and the pH, base excess (BE), and [HCO3-] levels were affected by the method of sacrifice: the lower the pH, BE, and [HCO3-] levels, the higher the fibrinolytic activity. Conversely, in experiments using the vascular perfusion technique, low pH, BE, and [HCO3-] levels of the perfusate induced abundant release of plasminogen activator from the vascular wall.

Male Wistar rats were treated with the carboxyl, thiol, and serine protease inhibitors, pepstatin, Ep-475[L-trans-epoxysuccinyl-leucylamide(3-methyl) butane; E-64-c], and chymostatin. Then the femoral muscles of these rats and control animals were used for preparation of myofibril proteins. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to analyze the degradation of these myofibril proteins with time (day) after death. The protease activities of the muscle were also measured. Tropomyosin was degraded most rapidly, followed by the heavy chain of myosin, alpha-actinin, and light chains of myosin (L1 and L2). Actin and troponin-T were degraded slowly, still remaining unchanged 2 weeks after death. The degradation of protein was not inhibited by pepstatin but was inhibited strongly by Ep-475 and very strongly by chymostatin. Chymostatin inhibited degradation of all components except alpha-actinin more strongly than Ep-475. Data on enzyme activities were consistent with these findings. These results suggest that after death the components of myofibrils are degraded with various proteases at various rates depending on their properties or their structure and that the proteases involved in the degradation show some specificity.

Studies were made on the acid-base balance, blood gases, and carbon monoxide (CO), cyanide, and sulfur dioxide concentrations in the blood of albino rabbits that died from automobile exhaust gas poisoning (group I) or fires in cars (complete combustion, group II; incomplete combustion, group III). In group I, the temperature and CO concentration increased gradually to 35 degrees C and 5.2% in 70 min. The animals died after 9 min, when the values were 20 degrees C and 5.2%, respectively. In group II the animals died after 9 min, when the values were 55 degrees C and 1.95%, respectively. In group III, the temperature was very high (870 degrees C), but the CO concentration was not (0.6-1.3%) after 4 min. The animals died after 5 min. In all experimental groups, marked acidosis and hypoxemia were seen, but the CO2 tension (PCO2) was high, in contrast to previous studies on pure CO poisoning. In group I, the level of carboxyhemoglobin (CO-Hb) was significantly higher (91.2 +/- 3.4% in arterial blood, 87.5 +/- 8.1% in venous blood; p less than 0.01) than in groups II and III. Although the O2 tensions of venous and arterial blood (PvO2, PaO2) were very low, that of arterial blood was higher, suggesting that O2 was still being utilized in the tissues at the time of death. In group II, CO-Hb was high (57.7 +/- 16.0% in arterial blood, 61.2 +/- 20.6% in venous blood) and the acid-base balance indicated marked acidosis. In group III, the CO-Hb, PCO2 and cyanide levels in the blood were very high.(ABSTRACT TRUNCATED AT 250 WORDS) Language: en