Li Ke-Gui, Cao Zhen-Dong, Peng Jiang-Lan, Fu Shi-Jian
Laboratory of Evolutionary Physiology and Behaviour, Chongqing Key Laboratory of Animal Biology, Chongqing Normal University, 400047 Chongqing, China.
J Comp Physiol B. 2010 Jun;180(5):661-71. doi: 10.1007/s00360-010-0443-4. Epub 2010 Feb 2.
Feeding and exhaustive exercise are known to elevate metabolism. However, acid-base status may be oppositely affected by the two processes. In this study, we first investigated the acid-base response of Chinese catfish to feeding (the meal size was about 8% of body mass) to test whether an alkaline tide (a metabolic alkalosis created by gastric HCl secretion after feeding) would occur. We then determined the combined effects of feeding and exhaustive exercise on excess post-exercise oxygen consumption and acid-base status to determine whether the alkaline tide induced by feeding protects against acid-base disturbance during exhaustive exercise and affects subsequent recovery. Arterial blood pH increased from 7.74 +/- 0.02 before feeding to 7.88 +/- 0.02 and plasma HCO(3)(-) increased from 5.42 +/- 0.29 to 7.83 +/- 0.37 mmol L(-1) 6 h after feeding, while feeding had no significant effect on PCO2. Exhaustive exercise led to a significant reduction in pH by 0.46 units and a reduction of HCO(3)(-) by approximately 3 mmol L(-1). Lactate concentrations in white muscle and plasma increased by 2.4 mmol L(-1) and 13.4 micromol g(-1), respectively. Fed fish had a higher pH and HCO(3)(-) than fasting fish at rest, and the reductions in pH (0.36 units) and HCO(3)(-) (approximately 2 mmol L(-1)) were thus lower after exhaustive exercise. However, the recovery of acid-base status and metabolites were similar in digesting and fasting fish. Overall, a significant alkaline tide was found in Chinese catfish after feeding. The alkaline tide elicited by feeding significantly prevented the decreases in pH and HCO(3)(-) immediately after exhaustive exercise, but recovery from exhaustive exercise was not affected by digestion.
已知进食和力竭运动可提高新陈代谢。然而，这两个过程对酸碱平衡状态的影响可能相反。在本研究中，我们首先研究了中华鲶对进食（食量约为体重的8%）的酸碱反应，以测试是否会出现碱潮（进食后胃分泌盐酸引起的代谢性碱中毒）。然后，我们确定了进食和力竭运动对运动后过量耗氧量和酸碱平衡状态的综合影响，以确定进食引起的碱潮是否能预防力竭运动期间的酸碱紊乱并影响随后的恢复。进食前动脉血pH值为7.74±0.02，进食6小时后升至7.88±0.02，血浆HCO₃⁻从5.42±0.29 mmol/L升至7.83±0.37 mmol/L，而进食对PCO₂无显著影响。力竭运动导致pH值显著降低0.46个单位，HCO₃⁻降低约3 mmol/L。白肌和血浆中的乳酸浓度分别增加了2.4 mmol/L和13.4 μmol/g。在休息时，进食的鱼比空腹的鱼具有更高的pH值和HCO₃⁻，因此力竭运动后pH值（0.36个单位）和HCO₃⁻（约2 mmol/L）的降低幅度较小。然而，消化中的鱼和空腹的鱼在酸碱平衡状态和代谢产物的恢复方面相似。总体而言，中华鲶进食后出现了显著的碱潮。进食引起的碱潮显著防止了力竭运动后立即出现的pH值和HCO₃⁻的下降，但力竭运动后的恢复不受消化的影响。
