Kelly Scott P, Wood Chris M
Department of Biology, Farquharson Life Science Building, York University, 4700 Keele Street, Toronto, ON, Canada M3J 1P3.
In Vitro Cell Dev Biol Anim. 2008 Mar-Apr;44(3-4):96-104. doi: 10.1007/s11626-007-9077-6. Epub 2008 Feb 1.
The effect of cortisol on calcium (Ca(2+)) transport across cultured rainbow trout gill epithelia composed of both pavement cells (PVCs) and mitochondria-rich cells (MRCs) was examined. Under symmetrical culture conditions (L15 media apical/L15 media basolateral), cortisol had subtle effects on gill epithelial preparations. Both control and cortisol treated epithelia exhibited Ca(2+) influx and efflux rates (measured radioisotopically using (45)Ca) that were approximately balanced, with a slight inwardly directed net Ca(2+) flux. Ussing flux ratio analysis indicated active Ca(2+) transport in the inward direction across epithelia bathed symmetrically regardless of hormone treatment. In contrast, under asymmetrical conditions (freshwater apical/L15 media basolateral) control epithelia exhibited active Ca(2+) transport in the outward direction (basolateral to apical) throughout experiments conducted over a 24-h period, whereas cortisol-treated preparations exhibited active transport in the inward direction (apical to basolateral) during the early stages of an asymmetrical culture period (e.g., T0-6 h) and passive transport during the later stages (e.g., T18-24 h). When soft freshwater (with tenfold lower [Ca(2+)]) was used for asymmetrical culture instead of freshwater, control epithelia developed outwardly directed active Ca(2+) transport properties, whereas cortisol-treated preparations did not. The results of this study support a hypercalcemic role for cortisol in rainbow trout and demonstrate that treating cultured gill epithelia composed of both PVCs and MRCs with cortisol can stimulate active Ca(2+) uptake under circumstances that more closely resemble natural conditions for fish gills (i.e., freshwater bathing the apical side of the epithelium).
研究了皮质醇对由扁平上皮细胞（PVCs）和富含线粒体的细胞（MRCs）组成的培养虹鳟鱼鳃上皮细胞钙（Ca(2+)）转运的影响。在对称培养条件下（L15培养基顶侧/L15培养基基底侧），皮质醇对鳃上皮细胞制剂有细微影响。对照和皮质醇处理的上皮细胞均表现出Ca(2+)流入和流出速率（使用(45)Ca通过放射性同位素测量）大致平衡，有轻微的内向净Ca(2+)通量。尤斯通量比率分析表明，无论激素处理如何，在对称浸泡的上皮细胞中，Ca(2+)均以内向方向进行主动转运。相比之下，在不对称条件下（淡水顶侧/L15培养基基底侧），对照上皮细胞在整个24小时实验期间均表现出外向（基底侧向顶侧）的Ca(2+)主动转运，而皮质醇处理的制剂在不对称培养期的早期阶段（例如，T0 - 6小时）表现出内向（顶侧向基底侧）的主动转运，在后期阶段（例如，T18 - 24小时）表现为被动转运。当使用软淡水（[Ca(2+)]低十倍）代替淡水进行不对称培养时，对照上皮细胞形成外向的Ca(2+)主动转运特性，而皮质醇处理的制剂则没有。本研究结果支持皮质醇在虹鳟鱼中具有高钙血症作用，并表明用皮质醇处理由PVCs和MRCs组成的培养鳃上皮细胞，在更接近鱼鳃自然条件（即淡水浸泡上皮细胞顶侧）的情况下可刺激Ca(2+)的主动摄取。
