Our understanding is limited on how fish adjust the effective permeability of their branchial epithelium to ions and water while altering O2 uptake rate (MO2) with acute and chronic changes in temperature. We investigated the effects of acclimation temperature (8 °C, 13 °C and 18 °C) and acute temperature challenges [acute rise (acclimated at 8 °C, measured at 13 °C and 18 °C), acute drop (acclimated at 18 °C, measured at 8 °C and 13 °C) and intermediate (acclimated at 13 °C, measured at 8 °C and 18 °C)] on routine MO2, diffusive water flux, and net sodium loss rates in 24-h fasted rainbow trout (Oncorhynchus mykiss). In the temperature challenge tests, measurements were made during the first hour. In acclimated trout at all temperatures, allometric mass scaling coefficients were much higher for diffusive water flux than for MO2. Furthermore, the diffusive water flux rate was more responsive (overall Q10 = 2.75) compared to MO2 (Q10 = 1.80) over the 8–18 °C range, and for both, Q10 values were greater at 8–13 °C than at 13–18 °C. The net Na+ flux rates were highly sensitive to acclimation temperature with an overall Q10 of 3.01 for 8–18 °C. In contrast, very different patterns occurred in trout subjected to acute temperature challenges. The net Na+ flux rate was temperature-insensitive with a Q10 around 1.0. Both MO2 and diffusive water flux rates exhibited lower Q10 values than for the acclimated rates in response to either acute increases or decreases in temperature. These results fit Pattern 5 of Precht (undercompensation, reverse effect) and more precisely Pattern IIB of Prosser (reverse translation). These inverse compensatory patterns suggest that trout do not alter their rates very much when undergoing acute thermal challenges (diurnal fluctuations, migration through the thermocline). The greater changes seen with acclimation may be adaptive to long-term seasonal changes in temperature. We discuss the roles of aquaporins, spontaneous activity, and recent feeding in these responses.

中文翻译：

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逆向翻译：适应温度和急性温度挑战对虹鳟鱼 (Oncorhynchus mykiss) 耗氧量、扩散水通量、净钠损失率、Q10 值和质量比例系数的影响

我们的理解仅限于鱼类如何调节其鳃上皮对离子和水的有效渗透性，同时随着温度的急性和慢性变化改变 O2 吸收率 (MO2)。我们研究了适应温度（8 °C、13 °C 和 18 °C）和急性温度挑战 [急性上升（在 8 °C 下驯化，在 13 °C 和 18 °C 下测量）、急性下降（在18 °C，在 8 °C 和 13 °C 下测量）和中间（在 13 °C 下适应，在 8 °C 和 18 °C 下测量）] 常规 MO2、扩散水通量和 24- h 禁食虹鳟鱼 (Oncorhynchus mykiss)。在温度挑战测试中，测量是在第一个小时内进行的。在所有温度下驯化的鳟鱼中，扩散水通量的异速生长质量比例系数远高于 MO2。此外，与 MO2 (Q10 = 1.80) 相比，在 8–18 °C 范围内，扩散水通量率更敏感（总体 Q10 = 2.75），并且对于两者而言，8–13 °C 下的 Q10 值大于 13–18 °C 下的 Q10 值℃。净 Na+ 通量速率对驯化温度高度敏感，8-18°C 的整体 Q10 为 3.01。相比之下，在经受剧烈温度挑战的鳟鱼中出现了截然不同的模式。净 Na+ 通量率对温度不敏感，Q10 约为 1.0。MO2 和扩散水通量率的 Q10 值均低于适应温度急剧升高或降低的适应率。这些结果符合 Precht 的模式 5（补偿不足、反向效应），更准确地说符合 Prosser 的模式 IIB（反向翻译）。这些逆向补偿模式表明，鳟鱼在经受剧烈的热挑战（昼夜波动、穿越温跃层的迁移）时不会改变它们的速率。驯化时看到的更大变化可能是适应温度的长期季节性变化。我们讨论了水通道蛋白、自发活动和最近进食在这些反应中的作用。