Collagen and collagenase in ulcer tissue--1. The healing process of acetic acid ulcers in rats.

We have reported that collagenase activity of the gastric mucosa increased significantly in acetic acid ulcers of dogs. The present study revealed that acetic acid ulcers in showed that the active collagenase level in the ulcer tissue increased rapidly with a peak (412.5%) on the 3rd day after induction of the acetic acid ulcer. Thereafter, the collagenase activity levels decreased gradually by the 7th day and returned practically to the control levels by the 14th day. On the other hand, collagen (hydroxyproline content) decreased by the 7th day (-16.5%) and recovered by the 14th day after induction of the acetic acid ulcer. The peak of active collagenase on the 3rd day coincident with the maximum ulcer index, suggesting involvement of collagenase activity in ulceration. In addition, destruction and production of collagen are considered to take place not only at the base of the ulcer and its margin, but also along its circumference.