Understand cellular mechanisms of secretory processes in exocrine glands and to elucidate age-related changes which affect these mechanisms. The broad objective of my research is to understand the cellular mechanisms of secretory processes in exocrine glands and to elucidate age-related changes which affect these mechanisms. The immediate goal is to determine how the synthesis of secretory proteins is regulated in the acinar cells and what age-related changes occur in this regulatory process. Using parotid glands of the rat as a modelsystem, we have determined that the rate of total protein synthesis declines progressively with age in this gland and that this decline largely reflects the reduced rate of synthesis of secretory proteins. We are currently investigating whether this decline reflects age-related changes in the cellular regulatory mechanism of secretory protein synthesis and whether this regulation involves changesin the level or activity of specific messenger RNA during translation. We use radioactivity incorporation analyses to quantitate messenger RNA activity following cell-free translation of parotid RNA. Specific translation products are immunoprecipitated or separated by gel electrophoresis. We also apply light and electron microscopy as well as cytochemical techniques, to characterize cellular changes during aging which affect synthesis and processing of newly synthesized secretory proteins.