Browsing by Subject "Type II cell"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Publication
    Open Access
    Stereologic analysis of the in vivo alveolar type II cell response to isoproterenol or saline administration
    (Murcia : F. Hernández, 1987) Smith, Dennis M.; Griffin, Lawrence S.
    Previous studies have demonstrated enhanced secretion of pulmonary surfactant from type I1 alveolar epithelial cells following 8-adrenergic stimulation. The present study was undertaken in order to provide quantitative morphologic data supporting this effect in vivo. Adult male Sprague-Dawley rats were injected subcutaneously with 150 mg/kg L-isoproterenol, a widerange 8-adrenergic agonist, and killed at times 0.25 - 12 hours post-injection. Other rats were similarly injected with saline, and killed at times 0.25 - 6 hours post-injection. A third group of animals was not injected, nor handled, prior to the time of death, and served as baseline controls. Stereologic analysis of the intracellular organelles of the type I1 celss in the animals treated with L-isoproterenol revealed a significant decrease in lamellar body volume density, indicating increased secretion of surfactant, at 0.5 - 4 hours. The rough endoplasmic reticulum volume density increased significantly at 2 - 6 hours, indicating increased synthetic activity. In contrast, the type I1 cells of salineinjected animals showed no significant evidence of increased secretion, but did demonstrate a large increase in synthetic activity, resulting in many large lamellar bodies at 2 and 4 hours post-injection. The results of this study provide quantitative morphological evidence of 8-adrenergic stimulation of the secretion and synthesis of pulmonary surfactant secretion by type I1 cells of the adult rat lung in vivo. In addition, they suggest an enhancement of surfactant synthesis following saline injection, which is perhaps based on endogenous catecholamine release.
  • Thumbnail Image
    Publication
    Open Access
    Ultrastructural changes in the synthetic and secretory patterns of pulmonary surfactant following pilocarpine in vivo
    (Murcia : F. Hernández, 1997) Smith, Dennis M.; Sommers Smith, Sally K.
    Previous studies have demonstrated that the muscarinic agonist pilocarpine stimulates the secretion of pulmonary surfactant from mammalian alveolar type 11 cells. The results of the present study quantify, via ultrastructural stereologic analysis, this response through 24 hours. The cytoplasmic volume density of lamellar bodies decreases significantly at 0.5 and 4 hours postinjection. This value is increased significantly at 12 hours post-injection. Elements of the secretory apparatus increase significantly at many of the post-injection times. At 12 hours post-injection many of the type 11 cells are quite laden with lamellar bodies, with some appearing surprisingly large. This may be a useful model for continued study of the relationship between synthesis and secretion of pulmonary surfactant.