Kinetics of Branchial Calcium Uptake in the Rainbow Trout: Effects of Acclimation to Various External Calcium Levels
Kinetics of Branchial Calcium Uptake in the Rainbow Trout: Effects of Acclimation to Various External Calcium Levels
复制标题
虹鳟鱼鳃钙吸收动力学：适应不同外部钙水平的影响
DOI：
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
C. Wood
中科院分区：
文献类型：
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作者：
S. Perry;C. Wood
在对照条件下（外部[Ca 2+ ]= 1.8 mequiv −1，[NaCl]= 0.8 mequiv 1 −1），淡水虹鳟鱼（萨尔莫gairdnen）体内通过鳃和全身体表的钙吸收速率（J Ca in）大致相等（12-15 μequiv kg −1 h −1）。内脏没有参与。在相同的条件下，在离体，盐水灌注头制备的鳃J Ca在体外是等于在体内。Ca中J的细胞主要位于鳃板上，而不是在鳃丝上，因为Ca中的J的95%发生在鳃的动脉-动脉循环。在体外，Ca中的J显示Michaelis-Menten动力学。适应于低外部[Ca 2+ ]（50 μequiv 1 −1 ;不变[NaCl]）1天导致Ca中J的5倍刺激，其特征为Km降低和Jmax增加。长时间的低[Ca 2+ ]驯化只引起Jmax的变化。随着驯化时间的增加，J max逐渐恢复到对照水平，但30天后仍升高。适应低环境[Ca 2+ ]引起的增殖和增加的板层氯细胞的暴露与增加的Jmax。暴露于高外部[Ca 2+ ]（10 mequivl −1 ;无变化[NaCl]）的鱼显示出Ca中J的减少，在体内实验中观察到Ca中J的类似变化。无论外部[Ca 2+ ]如何，血浆Ca 2+浓度保持恒定，而血浆Na +和Cl −水平在1天低[Ca 2+ ]暴露时短暂降低，但在7天后恢复。皮质醇刺激的板层氯细胞增殖和J在Ca的基础上的观察，并在低[Ca 2+ ]驯化的鱼血浆[皮质醇]升高，讨论了皮质醇在Ca 2+调节的可能作用。
Calcium uptake (J Ca in ) in freshwater rainbow trout ( Salmo gairdnen ) under control conditions (external [Ca 2+ ] ≃ 1.8 mequivl −1 , [NaCl] ≃ 0.8 mequiv 1 −1 ) occurred at approximately equal rates (12–15 μequiv kg −1 h −1 ) through the gills and the general body surface in vivo . The gut was not involved. Under the same conditions, in vitro branchial J Ca in in an isolated, saline-perfused head preparation was equal to that in vivo . The cells involved in J in Ca are mainly located on lamellae rather than on filaments since 95 % of J in Ca occurred across the arterio-arterial circulation of the gill. J in Ca , in vitro, displayed Michaelis-Menten kinetics. Acclimation to low external [Ca 2+ ] (50 μequiv 1 −1 ; unchanged [NaCl]) for 1 day caused a five-fold stimulation of J in Ca characterized by decreased K m and increased J max . Longer periods of low [Ca 2+ ] acclimation resulted in changes of J max only. J max gradually returned towards control levels as acclimation time increased, but was still elevated after 30 days. Acclimation to low ambient [Ca 2+ ] caused proliferation and increased exposure of lamellar chloride cells which were correlated with increased J max . Fish exposed to high external [Ca 2+ ] (10 mequivl −1 ; unchanged [NaCl]) displayed reduced J in Ca Similar changes in J in Ca were observed during in vivo experiments. Plasma Ca 2+ concentration remained constant regardless of external [Ca 2+ ], while plasma Na + and Cl − levels were transiently reduced at 1 day low [Ca 2+ ] exposure but had recovered by 7 days. A possible role for cortisol in Ca 2+ regulation is discussed based on observations of cortisol-stimulated lamellar chloride cell proliferation and J in Ca , and elevated plasma [cortisol] in low-[Ca 2+ ] acclimated fish.