Abstract

This study was undertaken to investigate the ultrastructural changes of the lung with special references to the alveolar lining cells of rats after inhalation anesthesia with ether, halothane and methoxyflurane respectively. The results were summarized as follow: 1) Light microscopically, the findings of lung tissue were very similar in the all groups. Immediately after anesthsia, mild congestion arid interstitial edema were noted. Four and 12 hours after anesthesia, the alveolar linings cells were increased in number with mild thickening of the alveolar septae. Increase of bronchiolar secretory activities were not prominent. 2) Electron microscopically, no significant change was noted in type I alveolar cell in the all groups. Most prominent changes were occurred in the type II alveolar cells in the all groups. with the ether anesthesia, marked changes of osmiophilic inclusion bodies, such as increased number, pleomorphism, decreased density and vacuolization were noted immediately after anesthesia. These changes were considerably recovered at 4 hours and completely returned to the normal pattern at 12 hours. Halothane and methoxyflurane anesthesis also induced similar changes in the type Ⅱ ceIls, but they were milder than ether anesthesized animals. Osmiophilic inclusion bodies were increased in number, with pleomorphism of the shape, decreased density, vacuolization and extrusion of their contents. After 4 and 12 hours, the number of type Ⅱ cells was also increased. The endothelial cells of alveolar capillaries showed nearly normal pictures in the ether anesthesized groups, but showed mild swelling, increase of pinocytotic vesicles, dilatation of rough ER and vacuolar formation in the both halothane and methoxyflurane anesthesized groups immediately after anesthesias. These changes were markedly recovered at 4 hours an completely returned to normal at 12 hours. The number of alveolar phagocytes were slightly increased in all experimental groups at 4 and 12 hours, with increase of autophagic vacuoles. 3) These findings suggest that ether anesthesia induces marked degenerative and adaptive changes in the alveolar type Ⅱ cells, particularly in their osmiophilic inclusion body, but does not effect alveolar capillary endothelial cells. On the other hand, halothane and methoxyflurane induce relatively milder degenerative and adaptive changes on the alveolar type Ⅱ cells, while mild degenerative changes are induced in the alveolar capillary endothelial cells. All these changes, occurred on the type Ⅱ epithelial cells and alveolar capillary endothelial cells, are reversible changes and times required for their recovery are relatively short.