Changes of salivary amylase in serum and parotid gland during pharmacological and physiological stimulation

Although serum amylase level is an important diagnostic factor in certain s alivary and pancreatic diseases, little information is available regarding the mechanism by which parotid amylase reaches the circulatory system. The present study was carried out to investigate the relationship between parot id isoamylase concentrations in blood serum and in parotid tissue in respon se to various stimuli. Wistar rats were fed with standard laboratory rodent chow; water was supplied ad libitum. In the first experiment, after a 16h fasting, rats received either 5 mg/kg pilocarpine or saline (control). In t he second study, after fasting, half of the rats were fed for I It, the oth er half received no food. In the third experiment, the changes in serum and tissue enzyme levels were monitored in freely fed animals during the peak- food intake phase, the first 2 It of the dark period. Amylase concentration was determined by using starch as a substrate. Pancreatic and parotid isoa mylase levels in serum were separated by gelelectrophoresis utilizing diffe rences in ionic properties of the isoenzymes. As expected, pilocarpine stro ngly stimulated tissue amylase discharge and serum amylase elevation. Simil ar, but less pronounced changes were observed not only during refeeding of fasted animals, but also in nonfasted rats during their peak-feeding period . Our data suggest that pharmacological stimulation, such as with pilocarpi ne or feeding in fasted state, as well as a mild stimulation of parotid fun ction by spontaneuous food intake during nonfasted state results in a decre ase in parotid tissue amylase activity and a proportional increase in serum levels of parotid isoamylase. (C) 2001 Published by Elsevier Science Ltd.