| The present study examined the functional and histological alterations of giunea pig gastric chief cells produced by y -irradiation, and the effects of misoprostol (MP), a prostaglandin E1 analogue, on these irradiation-induced damages. An attempt was also made to elucidate the mechanism of action of MP. The animals were divided into four groups: Group A: (control) not exposed to γ-irradiation; Group B:the epiqastrium was exposed to a single dose of γ-irradration at a dosage of 1,000 rad; Group C: oral ingestion of MP (divided into 50 μ g/kg/day and 100 μ g/kg/day two subgroups) was given prior to exposure of irradiation and once every day after irradiation for 14 days; Group D: MP (100 μ g/kg/day) was given once a day from 14th to 28th day after exposure to irradiation. Purified chief cells ( > 90%) were prepared from guinea pig stomach by digestion of gastric mucosa with crude collagenase following by incubation with EGTA. Pepsinogen secretion inresponse to the stimulation of 0.1 mM carbachol was used as an index of cell function and was measured by determining the peptic activity of extracellular medium by measuring the radioactivity released after incubation with 125I-bovine hemoglobin. Pepsinogen release is expressed as the ratio of the value of peptic activity in each experiment over the control value, i.e., pepsinogen release at the basal condition without stimulation of carbachol.Carbchol stimulated pepsinogen release from gastric chief cells in a dose dependent manner (10 -7...
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