[Cell-biological changes on the disordered tissues].

Abstract

In this study, we investigated cell-biologically the cell death generating by injuries, on the basis of two mechanisms of the cell death, these are necrosis and apoptosis. To heat the liver of rats, a heat device having a PID built-in electron regulator system was newly developed by us. The liver of rats laparotomized under anesthesia was heated at 37 degrees C, 50 degrees C and 65 degrees C for 5 min with a heated needle connected to the device, and thereafter the rats were survived in the given time. Appearance of the cell death in the tissue injured by heat was analyzed, in progress of the survival time, by means of staining of the tissue with hematoxylin-eosin (HE) and TUNEL method and agarosegel electrophoresis of DNA extracted from the tissue injured. Consequently, apoptosis appeared, in all heat temperatures, with bimodal pattern showing peak at about 2 and 10 hours after heat. Apoptosis in the first peak dottedly appeared, in heat temperature at 37 degrees C, in the whole region affected by heat. When the liver was heated at 50 degrees C and 65 degrees C, it first appeared on outer edge in the region affected by heat, and then made progress to the center of the region, condensation of chromatin was, in HE staining, remarkable at border between the injured and normal tissues. These findings were different from those in 37 degrees C. It seems that apoptosis in the first peak is caused by direct action of temperature. In the same time as the first peak of spoptosis appeared, appearance of HSP (heat shock protein) was observed. Apoptosis in the second peak, in all heat temperature, made progress from outer edge of the injured region to the center, time course of progression of the apoptosis was almost concurrent with that of infiltration of neutrophil to the injured region. Ladder formation was observed, when DNA extracted from the tissue showing apoptosis was applied for agarosegel electrophoresis. Necrosis in the injured tissue appeared in the same pattern with appearance of apoptosis in time course and on location, necrosis and apoptosis were observed in almost same degree up to appearance of the second peak of apoptosis. After 24 hours of heat, apoptotic cells were phagocytosed, only necrotic tissue remained. It seems that appearance of necrosis and apoptosis is caused by action of TNF alpha derived from neutrophils, since generation of TNF alpha was confirmed electron microscopically. In this study, it became cell-biologically evident that apoptosis is intensely concerned with cell death in the injured tissue.