Properties and localization of phospholipase A2 activity in rat stomach.
In the glandular stomach of rat, phospholipase A2 activity was detected and characterized by the use of sonicated 1-acyl-2-[1-14C]oleoyl-sn-glycero-3-phosphocholine (1 mM in 200 mM glycylglycine buffer/2 mM CaCl2) as substrate. The specific activity was 4.9 X 10(-2) mumol/min per mg protein in the whole glandular stomach homogenate (n = 8). It showed individual variation among rats. The optimal pH was 8.0. The activity was relatively heat-resistant and calcium-dependent. More than 90% of phospholipase A2 activity was located in the corpus and less than 10% was in the antrum. In the corpus wall, which consists of mucosa, submucosa, muscularis externa and serosa, the mucosal part (mucosa and submucosa) contained 80-90% of total activity. The effect of some clinical agents (ulcerogenic and anti-ulcer agents) on the phospholipase A2 activity was examined. The activity in the corpus was inhibited by cimetidine (50% inhibition at 5 X 10(-3) M) and stimulated by indomethacin (50% stimulation at 5 X 10(-5) M). Cetraxate hydrochloride (10(-6)-10(-3) M), 16,16-dimethylprostaglandin E2 (10(-7)-10(-4) M) and dexamethasone (10(-7)-10(-3) M) had no effect.
D000217:Acyltransferases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002927:Cimetidine / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D007700:Kinetics; D008245:Lysophospholipase / Q000378:metabolism; D008297:Male; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D051381:Rats; D013270:Stomach / Q000033:anatomy & histology / Q000201:enzymology*; D013379:Substrate Specificity; D014018:Tissue Distribution; D014148:Tranexamic Acid / Q000031:analogs & derivatives / Q000494:pharmacology
C000665:cetraxate; D014148:Tranexamic Acid; D002927:Cimetidine; D000217:Acyltransferases; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D008245:Lysophospholipase; D002118:Calcium; D007213:Indomethacin