The Changes Of Function And Ultrastructure Of Gastric Parietal Cells In Rats Under Stress Conditions And The Effect Of Acid Inhibitor On Them

Stress ulcer (SU) is a usual complication of clinical serious diseases and serious psychosis in clinic. It has a higher incidence and mortality, while its genesis mechanism is not very clear yet. At present, the scholars at home and abroad have performed a series of experiments and clinic studies on the genesis mechanism of SU and have made a great progress. It has been generally considered that many factors, such as weakened gastric mucosa defense, augmented impair factors and neurocrine imbalance, can induce SU. During the development of SU, gastric acid plays an important role and is believed the most common endogenetic damage factor. The purpose of this study was to investigate the dynamic changes of ultrastructure and function of gastric parietal cells and to observe the effects of omeprazole and cimetidine on the ultrastructure and function of gastric parietal cells in rats under water immersion-restraint stress (WRS) in order to probe the role of gastric acid during SU developing.1. The dynamic change of ultrastructure and function of gastric parietal cells in rats under stressObjective: To study the dynamic changes of ultrastructure and function of parietal cells in rats under stress and their correlation with acute gastric mucosal lesion.Methods: WRS model in SD rats was performed according to Brodie's method described previously. The extent of gastric mucosal lesion was evaluated grossly and histologically at WRS 1h, 2h, 4h according to the Guth standard. The pH value of gastric juice was measured by the pH/mV meter pH. The H+, K+-ATPase activity was determined by chemical colorimetry and inorganic phosphate assay. The histopathological change of gastric mucosa wasobserved by light microscope (LM) and the ultrastructural change of parietal cells was observed by transmission electron microscope (TEM).Results: 1. Gastric mucosal lesion: there was no lesion in control and a little spot erosion or hemorrhage in WRS 1h group. The gastric mucosal ulcer index (UI) was higher in WRS 1h group (9.5 2.98) than in control (p<0.01). Some mucosal shedding and necrosis were observed under LM. A little bloodstain and some scattered spot or lineal erosions and hemorrhage were observed in WRS 2h group. The UI ( 22.5 3.16) was higher in this group than in the former (p<0.01), and lots of necrosis, shedding and confusion were observed. In WRS 4h group, more bloodstain and scattered spot or lineal erosions, hemorrhage and ulcer were observed. The UI (35.0 3.93) was much higher (p<0.01), and more necrosis, shedding, hemorrhage, interruption and crateriform ulcer were observed. There was a positive relationship between UI and stress time (r=0.9876, p<0.01). The UI increased significantly with prolonged stress time. 2. Gastric juice pH value: The pH value was 2.56 0.14 in control and 2.26 0.40 in WRS 1h group with no statistical significant (p>0.05). The pH value of 1.81 0.25 in WRS 2h group was lower than control(p<0.01) and WRS 1h group(p<0.05), and 1.31 0.24 in WRS 4h group much lower than in other groups(p<0.01). There was a negative relationship between UI and pH(r=-0.9987, p<0.01). 3. H+, K+-ATPase activity (U/mg prot): Enzyme activity was 7.48 0.59 U/mg prot in control and 7.60 0.46 U/mg prot in WRS 1h group with no statistical significant (p>0.05). Activity of 7.81 0.24 U/mg prot was higher in WRS 2h group than in the formers (p>0.05), and 9.50 1.63 U/mg prot in WRS 4h group much higher than in other groups (p<0.05). 4. Ultrastructural changes of parietal cells: A resting state showing plenty of tubulovesicles and little of intracellular canaliculi lined with rare microvilli was observed in control. The beginning secreting state displaying intracellular canaliculi lined with short and little microvilli and plenty of vesicles around it was observed in WRS 1h group. A secreting state showing the increasing intracellular canaliculi and microvilli and the decreasing vesicleswas observed in WRS 2h group. An active secreting state displaying intracellular canaliculi lined with numerous microv...