Mechanisms of Na+ and C- regulation in freshwater-adapted rainbow trout (Oncorhynchus mykiss) during exercise and stress
Mechanisms of Na+ and C- regulation in freshwater-adapted rainbow trout (Oncorhynchus mykiss) during exercise and stress
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淡水适应虹鳟鱼 (Oncorhynchus mykiss) 在运动和应激过程中的 Na 和 C 调节机制
DOI：
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发表时间：
1995
影响因子：
2.8
通讯作者：
Mcdonald
中科院分区：
文献类型：
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作者：
Postlethwaite;Mcdonald
本研究探讨了运动和应激对淡水虹鱼体内Na~+和Cl~-的调节机制。有氧运动(大约2个身长的S-1)导致扩散性Na+流出短暂增加，血浆Na+和Cl-浓度短暂下降。这种干扰迅速被Na+和Cl-内流增加三倍(在运动的前10-12小时内)和通过运动7小时将Na+外流减少到控制值的40%而被迅速补偿。代偿使全身[Na+]显著升高，而全身[Cl-]无明显变化。相反，束缚应激(4h或8h)导致Na+和Cl-外流增加8倍，并持续到应激的前5h，导致全身[Na+]和[Cl-]大幅下降。这种损失的补偿直到应激后24小时才完成，并通过增加Na+和Cl-内流(与运动中观察到的幅度和时间相似)以及将Na+和Cl-外流减少到几乎为零来实现。我们得出的结论是，离子内流增加是因为鳃中不活跃的转运部位的激活，而外流则是由于鳃离子通透性的降低而减少；这两种反应都是由激素介导的。尽管激素控制机制目前还不清楚，但我们认为生长激素和催乳素分别负责调节内流和外流，并排除皮质醇或肾上腺素的任何作用，至少在运动中明显的快速[氯化钠]调节方面是这样。
This study examined the mechanisms by which Na+ and Cl- are regulated in freshwater rainbow trout during exercise and stress. Aerobic exercise (at approximately 2 body lengths s-1) caused a brief increase in diffusive Na+ efflux and a brief decline in plasma Na+ and Cl- concentrations. This disturbance was rapidly compensated by a threefold increase in Na+ and Cl- influx (over the first 1012 h of exercise) and by a reduction in Na+ efflux to 40 % of the control value by 7 h of exercise. The compensation produced a significant increase in whole-body [Na+], whereas whole-body [Cl-] remained unchanged. In contrast, confinement stress (for 4 or 8 h) caused an eightfold increase in Na+ and Cl- efflux which was sustained for at least the first 5 h of stress and resulted in large decreases in whole-body [Na+] and [Cl-]. Compensation of the losses was not complete until 24 h post-stress and was achieved by increases in Na+ and Cl- influx (of similar magnitude and timing to those observed during exercise) as well as reductions in Na+ and Cl- efflux to nearly zero. We conclude that ion influx increased because of an activation of inactive transport sites in the gills, whereas efflux was reduced by a reduction in branchial ionic permeability; both responses are mediated hormonally. Although the hormonal control mechanisms are as yet poorly defined, we argue that growth hormone and prolactin are responsible for the regulation of influx and efflux, respectively, and rule out either cortisol or epinephrine as having any role, at least with respect to the rapid [NaCl] regulation evident during exercise.