Biochemical background of the development of gastric mucosal damage in pylorus-ligated plus aspirin-treated rats.

Gastric mucosal damage was produced in rats after pyloric ligation by intragastric administration of 200 mg/kg aspirin diluted in 2 ml 150 mmol/l HCl. The animals in the control group received 2 ml saline solution, or submitted to pyloric ligation only. The animals were killed 4 h after the pyloric ligation, when the number and severity of gastric lesions (ulcers), and the gastric fundic mucosal level of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), cyclic adenosine monophosphate (cAMP) and lactate, were noted and measured. The adenylate pool (ATP + ADP + AMP) and the energy charge (ATP + 0.5ADP). (ATP + ADP + AMP)-1 were calculated. It was found that: the gastric H+ output decreased significantly in the pylorus-ligated plus aspirin-treated animals; the number and severity of gastric lesions increased significantly in the pylorus-ligated aspirin-treated animals; the extent of ATP transformation into the ADP decreased significantly in the pylorus-ligated aspirin-treated animals; the extent of ATP transformation into the cAMP decreased significantly during the aspirin treatment; the values of adenylate pool and of "energy charge" remained unchanged in the different groups of animals. It is concluded that: the decreased H+ output in the pylorus-ligated plus aspirin-treated group can be obtained by the decreased extent of ATP transformation into the ADP by membrane ATPase, and the biochemical changes in the gastric mucosa indicate a decreased energy turnover.