Ocean Sciences Centre, Memorial University, St. John's, NL, Canada A1C5S7.
Comp Biochem Physiol A Mol Integr Physiol. 2010 Feb;155(2):245-52. doi: 10.1016/j.cbpa.2009.11.006. Epub 2009 Nov 12.
Studies on how flatfish cardiovascular function responds to environmental challenges are limited, and have largely relied upon indirect methodologies (i.e. Fick principle). Thus, we measured dorsal aortic blood pressure (P(DA)) and cardiac function in 8 and 15 degrees C-acclimated flounder exposed to graded hypoxia, and in 8 degrees C-acclimated fish exposed to an acute temperature increase to their critical thermal maximum (CTM). The extent of bradycardia in 8 degrees C-acclimated fish (decrease in heart rate of 41%) was consistent with that observed for other teleosts, as was this species' CTM (25.8+/-0.5 degrees C) and its cardiac response to increasing temperature. However, this study provides further examples of how cardiovascular function is controlled differently in the flounder as compared with other fishes. First, the onset of bradycardia in 8 degrees C-acclimated fish occurred earlier than expected for this inactive and hypoxia-tolerant species (60% water air saturation). Second, resting cardiac output was similar in flounder acclimated to 8 and 15 degrees C (approximately 15 mL min(-1) kg(-1)), and hypoxic bradycardia was surprisingly absent at 15 degrees C. Finally, systemic vascular resistance decreased when flounder were exposed to elevated temperature, and this resulted in a 26% fall in P(DA). These are novel findings, however, the extent to which the flounder's behaviour influenced some of the results is unclear.
关于比目鱼心血管功能如何应对环境挑战的研究有限，并且在很大程度上依赖于间接方法（即 Fick 原理）。因此，我们在 8°C 和 15°C 适应温度下测量了比目鱼的背主动脉血压（P(DA)）和心功能，并在 8°C 适应温度下测量了比目鱼暴露于逐渐缺氧和急性温度升高至其临界热极值（CTM）时的心脏功能。8°C 适应温度下的比目鱼（心率降低 41%）的心动过缓程度与其他硬骨鱼的观察结果一致，该物种的 CTM（25.8+/-0.5°C）及其对温度升高的心脏反应也是如此。然而，这项研究提供了更多的例子，说明与其他鱼类相比，比目鱼的心血管功能是如何不同的。首先，8°C 适应温度的比目鱼的心动过缓发生得比预期的这种不活跃和耐缺氧的物种更早（60%水空气饱和度）。其次，在 8°C 和 15°C 适应的比目鱼的静息心输出量相似（约 15 毫升/分钟/千克），并且在 15°C 时，令人惊讶的是没有缺氧性心动过缓。最后，当比目鱼暴露于高温时，全身血管阻力降低，导致 P(DA)下降 26%。这些都是新的发现，然而，比目鱼的行为在多大程度上影响了一些结果尚不清楚。
