Brauner C J, Matey V, Zhang W, Richards J G, Dhillon R, Cao Z-D, Wang Y, Fu S-J
Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia V6T 1Z4, Canada.
Physiol Biochem Zool. 2011 Nov-Dec;84(6):535-42. doi: 10.1086/662664. Epub 2011 Oct 14.
Gill remodeling can be extensive in crucian carp, where up to a 7.5-fold increase in gill surface area has been observed during exposure to hypoxia through a reduction in the interlamellar cell mass (ILCM) and increased lamellar protrusion that has been hypothesized to be signaled by the need to maximize oxygen uptake under a given condition. Sustained aerobic exercise may have the greatest influence on oxygen demand in fish; however, its effect on gill remodeling in crucian carp has not been investigated. The specific objectives of this study were to determine (i) whether sustained aerobic exercise induces gill remodeling in the crucian carp, (ii) whether gill remodeling following sustained exercise affects the maximum critical swimming speed (U(crit)) and maximal oxygen consumption rate ([Formula: see text]), and (iii) whether gill remodeling following sustained exercise is associated with trade-offs related to ionoregulation. We measured [Formula: see text] in crucian carp at each step during an initial U(crit) test (U(crit1)), forced them to swim at 70% of U(crit) for 40 h, and then conducted a second U(crit) test (U(crit2)). From rest to U(crit1) (7-8 h), we observed a significant increase in protruding lamella height and area of the gills and a reduction in ILCM height and volume, likely associated with partial shedding of the ILCM, indicating that gill remodeling during exercise is rapid. Further changes were observed between U(crit1) and U(crit2), with statistically significant increases in protruding lamellar height, basal length and area, and a statistically significant reduction in protruding lamellar thickness and ILCM height and volume. Interestingly, there was no significant difference between U(crit1) and U(crit2) values, nor in maximal [Formula: see text] measured at U(crit1) and U(crit2). Furthermore, there was no significant difference in plasma osmolarity, [Na(+)], or [Cl(-)] in fish at rest, following U(crit1) or U(crit2). Thus, while these data support the hypothesis that the need to maximize oxygen uptake is an important signal for gill remodeling, which can occur quite rapidly (within 7 h at 15°C), the physiological implications of remodeling during exercise are less clear.
鲫鱼的鳃重塑可能很广泛，在暴露于低氧环境期间，通过减少板间细胞团（ILCM）以及增加鳃小片突出，观察到鳃表面积增加了7.5倍，据推测这是由在特定条件下最大化氧气摄取的需求所引发的信号。持续有氧运动可能对鱼类的氧气需求影响最大；然而，其对鲫鱼鳃重塑的影响尚未得到研究。本研究的具体目标是确定：（i）持续有氧运动是否会诱导鲫鱼的鳃重塑；（ii）持续运动后的鳃重塑是否会影响最大临界游泳速度（U(crit)）和最大耗氧率（[公式：见原文]）；（iii）持续运动后的鳃重塑是否与离子调节相关的权衡有关。我们在初始U(crit)测试（U(crit1)）的每个步骤中测量鲫鱼的[公式：见原文]，迫使它们以U(crit)的70%游泳40小时，然后进行第二次U(crit)测试（U(crit2)）。从静止到U(crit1)（7 - 8小时），我们观察到鳃的突出鳃小片高度和面积显著增加，ILCM高度和体积减小，这可能与ILCM的部分脱落有关，表明运动期间的鳃重塑很快。在U(crit1)和U(crit2)之间观察到了进一步的变化，突出鳃小片高度、基部长度和面积有统计学显著增加，突出鳃小片厚度以及ILCM高度和体积有统计学显著减小。有趣的是，U(crit1)和U(crit2)的值之间没有显著差异，在U(crit1)和U(crit2)测量的最大[公式：见原文]也没有显著差异。此外，在静止、U(crit1)或U(crit2)后，鱼的血浆渗透压、[Na(+)]或[Cl(-)]没有显著差异。因此，虽然这些数据支持这样的假设，即最大化氧气摄取的需求是鳃重塑的一个重要信号（在15°C下可在7小时内相当迅速地发生），但运动期间重塑的生理意义尚不清楚。
