Parotid gland recovery from an obstruction--changes of amylase release from the tissue

The recovery of the parotid gland in the rat was studied by isoproterenol-induced amylase release from the parotid tissue in vitro after the removal of duct ligation following 2 and 7 days of obstruction. The percentage of amylase release did not change, but the activity of amylase in the medium (the released amylase activity) increased gradually after the removal of ligation. When the duct was ligated for 2 days, a complete recovery of the released amylase activity was seen 21 days after the removal of ligature. However, in the case of 7-day-ligation, the recovery was about 70 percent after the same period. An obstruction of a shorter duration produced a more rapid recovery of amylase release. Amylase activity in the parotid tissue increased gradually with time after the removal of ligature, and the recovery rates were very similar to that of the released amylase activity. The present results suggest that the recovery of released amylase activity after the removal of ligature is due to the increase of amylase content in the parotid tissue.