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ナキウサギ(Pika, Whistle rabbit)の弱熱放散能

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Title: ナキウサギ(Pika, Whistle rabbit)の弱熱放散能
Other Titles: Poor Heat Loss Ability of Pika (Whistle Rabbit)
Authors: 楊, 果杰 / 松本, 孝朗 / 小坂, 光男 / 山内, 正毅 / 大渡, 伸
Authors (alternative): Yang, Guo-Jie / Matsumoto, Takaaki / Kosaka, Mitsuo / Yamauchi, Masaki / Ohwatari, Nobu
Issue Date: 31-Mar-1988
Publisher: 長崎大学熱帯医学研究所 / Institute of Tropical Medicine, Nagasaki University
Citation: 熱帯医学 Tropical medicine 30(1). p45-48, 1988
Abstract: ナキウサギ(Pika, Whistle rabbit)は,氷河時代を生き抜いた古いウサギであり特徴的な短く丸い耳を持っている.我々はこのナキウサギを飼育し,その代謝や体温が高く,また外因性発熱物質であるLPS-pyrogenにより発熱性を有することを報告してきた.今回,ナキウサギの熱放散能について検討した.30℃および33℃,相対湿度60%の環境条件にて,家兎ではパンティング(浅速呼吸)が出現したのに対し,ナキウサギではその呼吸数は全く増加しなかった.さらに注目すべきことに,40℃,相対湿度60%では,ナキウサギの直腸温は,急速に上昇し,遂には一羽では44.0℃,もう一羽では実験中止一時間後43.1℃となり死亡した.他方,この実験により死亡する家兎はいなかった.また,家兎の主たる熱放散機構は,パンティング及びその長い耳からの放熱であるが,ナキウサギの耳は小さく,因にその体表面積あたりの比率は,家兎17%に対し7%にすぎない.このように,ナキウサギの熱放散能は乏しく,それは熱放散器官である耳の面積が小さいこととパンティングの欠如によると考えられる. / Pikas (Whistle rabbit) are old-fashioned rabbits which had survived the Age of Ice, and have characteristic short rounded ears. We have reared pikas since 1985 and reported their higher metabolic rate, higher body temperature and pyrogenic response (intravenous lipopolysaccharide pyrogen) previously. In the present experiment pika's heat loss ability was examined and discussed from the view point of thermoregulation. During heat exposure (30℃, 33℃, and 40℃, 60%rh), thermal panting was observed in rabbits, however, no increase in respiratory rate was observed in pikas. Noteworthily two pikas rapidly increased the rectal temperature at heat exposure (40℃, 60%rh) and then finally died after 90min, of which rectal temperature was 44.0℃ and 43.1℃, respectively. Laboratory albino rabbits survived this experiment. Though the radiation from ear surface is the main heat loss mechanism for rabbits, the ear surface area ratio to body surface area in pikas was small compared to rabbits. It was 7% in pikas and 17% in rabbits. These results revealed the poor heat loss ability in pikas constituted by smallness of ear surface area and lack of thermal panting.
URI: http://hdl.handle.net/10069/4514
ISSN: 03855643
Type: Departmental Bulletin Paper
Appears in Collections:Volume 30, No. 1

Citable URI : http://hdl.handle.net/10069/4514

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