| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
1. A method for preparing isolated enriched parietal cells from rabbit gastric mucosa has been developed. As judged by ^<14>C-aminopyrine uptake, these cells showed an excellent response to various secretagogues, including histamine, carbachol, and gastrin.
2. Using these cells, secretagogue-induced changes in cellular messengers, cAMP and free calcium were determined. Histamine increased cellular cAMP which failed to respond to other secretagogues. In contrast, histamine, carbachol and gastrin brought about a rapid elevation of cellular free calcium. This response appeared to be mediated by independent receptor mechanisms.
3. The binding of ^3H-histamine to isolated rabbit parietal cells was studied. However, from the experiments using various histamine receptor antagonists, the binding of ^3H-histamine did not appear to represent the actual receptor binding.
4. The composition and ctructure of membrane glycolipids of parietal cells were analyzed. Sulfated glycolipids were found to be preferentially enriched in the acid-secreting mucosa and parietal cells.
5. Staining with fluorescent-labelled phalloin and with indirect immunofluorescence using specific antibodies to actin, close structural association of microfilaments with intracellular canaliculi was revealed. Moreover, inhibotors of microfilament such as cytochalasin D strongly inhibited acid secretion irrespective of the secretagogues. Since these microfilaments-disrupting agents did not influence the response at the second messengers, the inhibition by these agents should be attributed to the mechanisms distal to the level of second messengers.
6. The gastric vesicles containing highly enriched H^+,K^+-ATPase has been prepared by differential centrifugation and dentity gradient ultracentrifugation. Polyclonal antibodies specific to H^+,K^+-ATPase were raised in rabbits.
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