Amylase in the saliva and in the gastric aspirates of premature infants: its potential role in glucose polymer hydrolysis.

Amylase activity was found in saliva from 13 infants, 26-42 wk corrected gestational age. The levels of salivary amylase activity increased with advancing age. In 10 infants, 31-38 wk corrected gestational age (estimated gestational age in wk plus age in wk after birth), gastric aspirates collected before a feeding and sequentially at 30-min intervals after two consecutive feedings were analyzed for amylase activity and pH. Two different postprandial patterns were obtained. For six of the 10 infants, both the pH and amylase activities of their gastric aspirates showed a distinct maxima at about 60 min after a feeding and a minima at 180 min just before the second feeding. In the remaining four infants, the pHs of their gastric aspirates remained relatively high (5.0-6.0) for the entire postprandial period. In these infants, there was a persistently high level of the amylase activity. In all 10 infants, amylase activity was found in their gastric aspirate samples when the pH was above 3.0. Comparison of the amylase in the gastric aspirate with purified pancreatic and salivary amylases by polyacrylamide gel electrophoresis showed that the amylase in the gastric aspirate has an electrophoretic mobility similar to that of salivary amylase, which suggests a salivary origin. This study supports the possibility that salivary amylase could enter the stomach and retain a significant amount of its activity in premature infants.