著者

山下 雅道 内藤 富夫 Wassersug Richard J.

出版者

日本宇宙生物科学会

雑誌

Biological Sciences in Space (ISSN:09149201)

巻号頁・発行日

vol.16, no.4, pp.245-270, 2002 (Released:2006-01-31)

参考文献数

94

被引用文献数

1 1

---

We review here the scientific significance of the use of amphibians for research in gravitational biology. Since amphibian eggs are quite large, yet develop rapidly and externally, it is easy to observe their development. Consequently amphibians were the first vertebrates to have their early developmental processes investigated in space. Though several deviations from normal embryonic development occur when amphibians are raised in microgravity, their developmental program is robust enough to return the organisms to an ostensibly normal morphology by the time they hatch. Evolutionally, amphibians were the first vertebrate animal to come out of the water and onto land. Subsequently they diversified and have adaptively radiated to various habitats. They now inhabit aquatic, terrestrial, arboreal and fossorial niches. This diversity can be used to help study the biological effects of gravity at the organismal level, where macroscopic phenomena are associated with gravitational loading. By choosing different amphibian models and using a comparative approach one can effectively identify the action of gravity on biological systems, and the adaptation that vertebrates have made to this loading. Advances in cellular and molecular biology provide powerful tools for the study in many fields, including gravitational biology, and amphibians have proven to be good models for studies at those levels as well. The low metabolic rates of amphibians make them convenient organisms to work with (compared to birds and mammals) in the difficult and confined spaces on orbiting research platforms. We include here a review of what is known about and the potential for further behavioral and physiological researches in space using amphibians.

著者

福原 武 内藤 富夫 亀山 博子

出版者

日本平滑筋学会

雑誌

日本平滑筋学会雑誌 (ISSN:03743527)

巻号頁・発行日

vol.9, no.1, pp.1-8, 1973-03-01 (Released:2010-07-21)

参考文献数

13

被引用文献数

2 3

---

1.カエルの喉門・食道開口附近の粘膜を機械的に刺激すると, 腹筋が急に強縮をおこし, 口中に食道と胃が裏返しになって出てくる.この際胃の運動高進は, 認められない.この口中への胃の脱出の機序は, つぎのようなものであろう.まず腹筋の強縮によって, 腹圧が突然に高まり, その結果として胃が押しあげられ, ついに食道内に嵌入するのである.このことから, カエルにおいては, 嘔吐は胃の収縮によってではなく, 全く腹筋の収縮によって起こるものと考えられる.2.0.05g/mlの濃度を有する吐酒石-Ringer液の0.5ml (トノサマガエル) あるいは5ml (ウシガエル) を胃内腔に注入すると, 食道と胃の脱出ばかりでなく, 胃の運動の高進が起こる.脳脊髄破壊カエルでは食道・胃の脱出は起こらないが, 胃の運動高進効果は認められる.したがってこの高進効果は薬物が直接胃壁に作用してひき起こされたものと考えられる.