Changes in synthetic activity of sulfated mucosubstances in healing process of acetic acid ulcer in rats and effect of anti-ulcer agents.

It is generally believed that ulcerogenesis results from an imbalance between the aggressive and defensive factors (1). Recently, increasing interest is being shown regarding the importance of anti-ulcer therapy, presumably via the positive effects on the defensive mechanisms. Attention has been paid to the function of mucosubstances including sulfated mucosubstances (SMS) as participators in the mucosal defensive system. Previous investigations on the function of SMS have been carried out by using acute gastric ulcers such as stress or drug-induced ulcers (2-4). However, there is little information about the role of SMS in chronic gastric ulcers. The present study was undertaken to investigate the changes in the synthetic activity of SMS in the ulcerated tissue during the healing process of acetic acid ulcer and the effect of some anti-ulcer agents, using the 35S-sulfate as the index for the SMS biosynthesis. Male Wistar strain rats weighing approx. 180 g were used. The acetic acid ulcers, 4 mm in diam., were produced by the application of glacial acetic acid to the serosal surface of the stomach as reported by Okabe et al. (5). The rats were orally given the anti-ulcer agents, suspended in 0.4% carboxymethylcelIulose (CIVIC), for 5 days starting from 1 day or 15 days after the operation. One hour after the last dosing, approx. 100 /CCI of Nat 35S04 (The Radiochemical Centre , Amer sham) was injected intraperitoneally and the stomach removed 6 hr later. The ulcerated area was macroscopically measured in rats sacrificed 20 days after the operation. The tissues of the ulcerated portion were punched out in circular forms, 14 mm in diam., to make the tissues similar in size. The rate of incor poration of the 35S-sulfate into gastric SMS was determined according to the method of Rainsford (3). In brief, the tissues obtained were homogenized with a Physcotron in water, and three volumes of ice-cold ethanol were added to the homogenate. After allowing this to stand overnight at 4°C, the precipitate following centrifugation was defatted with 5 ml of ether-acetone (1 :1, v/v). The resultant dry tissue was weighed, suspended in 1 ml of water and digested with papain (2x crystallized, Sigma) at 65'C for 24 hr. After digestion, SMS was isolated and washed free of low molecular substances using a Millipore filter (0.4 ,um pore, Millipore Corp.) with 30 ml aliquots of 0.1 M Na2SO4+0.1 M H2SO4, 0.1 M Na2SO4 and water in suc cession. The …