Methemoglobin is hemoglobin containing ferric iron rather than ferrous iron which renders it incapable of binding to oxygen. Blood sampling of fish is done under sedation or general anesthesia. Tricaine methanesulfonate (TMS) or benzocaine is commonly used but both can cause oxidation of hemoglobin to methemoglobin. Our objective was to determine if methemoglobin concentrations in healthy rainbow trout ( Oncorhynchus mykiss ), brook trout ( Salvelinus fontinalis ), or Atlantic salmon ( Salmo salar ) increase during sedation with 25 mg/L of a 10% benzocaine solution or with repeated short anesthetizations by 65 mg/L of 10% benzocaine solution or 65 mg/L of TMS. Sedation by benzocaine caused a significant increase in methemoglobin in all species over time ( P <  0.05). The methemoglobin percentage in brook trout increased by 129%, rainbow trout by 42%, and Atlantic salmon by 49%. The methemoglobin in brook trout was significantly greater than the other species at multiple time points. Repeated brief anesthetizing by benzocaine and TMS caused significant methemoglobin by 60 ( P <  0.05), 90 ( P <  0.01), and 120 min ( P <  0.001) in brook trout but no significant change in methemoglobin in rainbow trout or Atlantic salmon except at 120 min in Atlantic salmon ( P  < 0.05) repeatedly anesthetized with benzocaine. For example, following multiple anesthetizations with benzocaine, the methemoglobin percentage in brook trout increased by 140%, whereas the rise in methemoglobin in rainbow trout and Atlantic salmon was more modest (37% increase in Rainbow trout and 53% increase in Atlantic salmon). Following multiple anesthetizations with TMS, the methemoglobin increased by 90%, 5%, and 1% in brook trout, rainbow trout, and Atlantic salmon, respectively. Methemoglobin may increase significantly over time in fish immersed in a sedating dose of benzocaine or repeatedly anesthetized with benzocaine or TMS. The susceptibility varies with the individual and species with brook trout being more susceptible than Atlantic salmon or rainbow trout.

中文翻译：

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暴露于苯佐卡因或三卡因甲磺酸盐后三种鲑鱼物种中的高铁血红蛋白浓度

高铁血红蛋白是含有铁血红蛋白而不是亚铁的血红蛋白，这使其无法与氧气结合。鱼的血液采样是在镇静或全身麻醉下进行的。普遍使用曲卡因甲磺酸盐（TMS）或苯佐卡因，但两者均可引起血红蛋白氧化为高铁血红蛋白。我们的目标是确定健康虹鳟（ Oncorhynchus mykiss ），溪鳟（ Salvelinus fontinalis ）或大西洋鲑（ Salmo salar ）中的 高铁血红蛋白浓度 ）在镇静期间使用25 mg / L的10％苯佐卡因溶液或反复反复麻醉可增加65 mg / L的10％苯卡因溶液或65 mg / L TMS。随着时间的推移，苯佐卡因的镇静作用使所有物种的高铁血红蛋白显着增加（ P <  0.05）。溪鳟的高铁血红蛋白百分比增加了129％，虹鳟增加了42％，大西洋鲑增加了49％。溪鳟中的高铁血红蛋白在多个时间点显着大于其他物种。苯佐卡因和TMS反复短暂麻醉会在60（ P <  0.05），90（ P <  0.01）和120 min（ P <  在河鳟中为0.001），但在虹鳟鱼或大西洋鲑中，高铁血红蛋白没有显着变化，但在大西洋鲑中为120分钟（ P  <0.05）反复用苯佐卡因麻醉。例如，在用苯佐卡因多次麻醉后，河鳟中的高铁血红蛋白百分比增加了140％，而虹鳟鱼和大西洋鲑中的高铁血红蛋白的上升幅度则较小（虹鳟鱼中的高铁血红蛋白增加了37％，大西洋鲑鱼中的高铁血红蛋白增加了53％）。经过TMS多次麻醉后，溪鳟，虹鳟和大西洋鲑的高铁血红蛋白分别增加了90％，5％和1％。浸泡在镇静剂量的苯佐卡因中或用苯佐卡因或TMS反复麻醉的鱼中，高铁血红蛋白可能会随时间显着增加。易感性随个体和物种而变化，溪鳟比大西洋鲑或虹鳟更易感。