Exocrine Protein Secretion from Human Parotid Glands during Aging: Stable Release of the Acidic Proline-Rich Proteins

Exocrine protein secretion from stimulated human parotid glands was examined in 220 adults, 20 to 88 years old. A group of parotid proteins, the anionic proline-rich proteins (PRP), was used as a marker for studying protein exocytosis. Data were evaluated as the salivary concentration of PRP (mg%), the percentage of total parotid salivary protein represented by the PRP and as total PRP output (mg/min). No differences were observed in the ability of different-aged males and females to secrete this group of exocrine secretory proteins.