Chattonella marina赤潮に暴露した魚の鰓carbonic anhydrase活性の変化-魚のへい死と関連して〔英文〕

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The activities of carbonic anhydrase (EC 4. 2. 1. 1) in the gills of yellowtail Seriola quinqueradiata and red sea bream Pagrus major exposed to Chattonella marina red tide were measured. When yellowtail and red sea bream were exposed to the seawater containing C. marina of 2, 900 and 6, 500 cells/ml, respectively, the gill enzyme activities were rapidly decreased. After about 40 min, these were not detectable. To simulate this phenomenon by inhibiting gill carbonic anhydrase in vivo, yellowtail were exposed to the seawater containing 0.2mM acetazolamide, a potent and specific inhibitor of the enzyme, and 5 ppm Triton X-100 which was used to remove the mucus from the gills. The fish swam violently in proportion to the duration of exposure and were fatal in about 60 min. After 60 min, the oxygen partial pressure in the arterial blood was reduced to 25-40% of the pre-exposure value. Judging from these results, the reduction of carbonic anhydrase activity in the gills may be one of the principal causes of mortality by the exposure of fish to C. marina.