Gill Remodeling in Crucian Carp during Sustained Exercise and the Effect on Subsequent Swimming Performance

• Published in: Physiological and biochemical zoology 2011-11, Vol.84 (6), p.535-542
• Main Authors: Brauner, C. J., Matey, V., Zhang, W., Richards, J. G., Dhillon, R., Cao, Z.-D., Wang, Y., Fu, S.-J.
• Format: Article
• Language: English
• Subjects: Airway Remodeling - physiology; Animals; Blood plasma; Carp; Carps - blood; Carps - physiology; Fatigue; Freshwater; Gills; Gills - anatomy & histology; Gills - physiology; Hematocrit; Hypoxia; Osmolar Concentration; Oxygen; Oxygen Consumption; Physical Conditioning, Animal - physiology; Renovations; Surface areas; Swimming; Swimming - physiology; Task Performance and Analysis
• ISSN: 1522-2152; 1537-5293
• DOI: 10.1086/662664

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 ( ), and (iii) whether gill remodeling following sustained exercise is associated with trade-offs related to ionoregulation. We measured in crucian carp at each step during an initialU crittest (U crit1), forced them to swim at 70% ofU critfor 40 h, and then conducted a secondU crittest (U crit2). From rest toU 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 betweenU crit1andU 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 betweenU crit1andU crit2values, nor in maximal measured atU crit1andU crit2. Furthermore, there was no significant difference in plasma osmolarity, [Na+], or [Cl−] in fish at rest, followingU crit1orU 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.