Department of Biology, University of New Brunswick, Saint John, NB, Canada.
Fish Physiol Biochem. 2011 Dec;37(4):809-19. doi: 10.1007/s10695-011-9479-y. Epub 2011 Apr 3.
Atlantic sturgeon (Acipenser oxyrhynchus), which are bottom dwelling and migratory fish, experience environmental hypoxia in their natural environment. Atlantic sturgeon, acclimated to either 5 or 15°C, were subjected to a 1 h severe (<10 mm Hg) hypoxia challenge in order to document their physiological responses. We measured hematological parameters, including O(2) transport (hemoglobin, hematocrit), ionic (chloride, osmolality), and metabolic (glucose, lactate) variables under normoxic conditions (~160 mm Hg), immediately following a 1 h exposure to hypoxic water, and following a further 2 h of recovery from this challenge in normoxic water. In a second experiment, we assessed the opercular beat frequency before, during, and after hypoxic exposure. Hemoglobin concentrations and hematocrit were significantly different between fish held at 5°C vs. 15°C and also significantly different between normoxia prior to hypoxia and following recovery. Plasma lactate concentrations increased following hypoxia at both temperatures, indicative of an increase in anaerobic metabolism. In contrast, a significant increase in plasma glucose concentrations in response to hypoxia only occurred at 5°C, suggesting different fuel demands under different temperatures. Changes in opercular beat frequency (OBF) were dependent on temperature. At 5°C, OBF increased upon exposure to hypoxia, but returned to pre-exposure levels within 35 min for the remainder of the experiment. During hypoxia at 15°C, OBF increased very briefly, but then rapidly (within 20 min) decreased to levels below control values. Following a return to normoxia, OBF quickly increased to control levels. Overall, these findings suggest that Atlantic sturgeons are relatively tolerant to short-term and severe hypoxic stress, and the strategies for hypoxia tolerance may be temperature dependent.
大西洋鲟（Acipenser oxyrhynchus）是底栖洄游鱼类，在自然环境中会经历缺氧环境。为了记录它们的生理反应，我们将适应 5°C 或 15°C 的大西洋鲟置于严重缺氧（<10 毫米汞柱）环境中 1 小时。我们在正常氧合条件下（~160 毫米汞柱）测量了血液学参数，包括氧气运输（血红蛋白、血细胞比容）、离子（氯、渗透压）和代谢（葡萄糖、乳酸）变量，在 1 小时暴露于缺氧水中后立即测量，然后在正常水中从该挑战中恢复 2 小时后再次测量。在第二个实验中，我们在缺氧暴露之前、期间和之后评估了鳃盖拍动频率。血红蛋白浓度和血细胞比容在 5°C 和 15°C 之间以及在缺氧前的正常氧合和恢复后的正常氧合之间有显著差异。在两种温度下，缺氧后血浆乳酸浓度均升高，表明无氧代谢增加。相比之下，只有在 5°C 下，缺氧后血浆葡萄糖浓度显著增加，表明在不同温度下有不同的燃料需求。鳃盖拍动频率（OBF）的变化取决于温度。在 5°C 时，OBF 在暴露于缺氧时增加，但在实验的其余时间内，在 35 分钟内恢复到暴露前的水平。在 15°C 时的缺氧期间，OBF 短暂增加，但随后迅速（在 20 分钟内）降至低于对照值的水平。在返回正常氧合后，OBF 迅速恢复到对照水平。总的来说，这些发现表明大西洋鲟对短期和严重的缺氧应激相对耐受，而对缺氧的耐受策略可能依赖于温度。
