Secretory granules are the subcellular organelles in which the salivary parenchymal cells store their secretory products until such time that they are released into the oral cavity. Secretory granule maturation is believed to be an important step in the formation of these granules and is thought to be comprised of the condensation of macromolecular and other secretory products into these discrete package. Little is known of this step in the secretory cycle of salivary glands, and yet it may be an essential and highly significant aspect of normal salivary gland function, and hence, oral health. The overall objective of this study is to determine the nature of the changes that secretory granules undergo during maturation, and to elucidate the cellular mechanisms by which this maturation process occurs. This will be accomplished in part, but not totally, by utilizing a model system consisting of rat parotid secretory granules of differing buoyant densities, the less dense of which appears to be a precursor of the precursor of the denser population of granules based on pulse labelling studies.
The specific aims are to characterize these two types of secretory granules by direct measurement of their volumes and concentrations of macromolecular and inorganic components. Qualitative comparisons of the proteins, glycoproteins, and sulfated macromolecules such as glycosaminoglycans, in addition to quantitative determinations, will be carried out. Two possible mechanisms for secretory granule maturation via the lowering of the colligative properties of the contents will be tested for. These are: 1) the complexing of macromolecules with or without the intermediation of ions, and 2) the pumping of ions out of the granules so that water will follow, or into the granules in order to promote intermolecular complexing. In situ granule studies will also be carried out in order to verify the findings using isolated secretory granules.
| Izutsu, K T; Cantino, M E; Johnson, D E (1994) A review of electron probe X-ray microanalysis studies of salivary gland cells. Microsc Res Tech 27:71-9 |
| Ball, W D; Hand, A R; Moreira, J E et al. (1993) The B1-immunoreactive proteins of the perinatal submandibular gland: similarity to the major parotid gland protein, RPSP. Crit Rev Oral Biol Med 4:517-24 |
| Wong, J G; Izutsu, K T; Robinovitch, M R et al. (1991) Microprobe analysis of maturation-related elemental changes in rat parotid secretory granules. Am J Physiol 261:C1033-41 |
