Doyle D, Carney Almroth B, Sundell K, Simopoulou N, Sundh H
Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
Front Physiol. 2022 May 13;13:882973. doi: 10.3389/fphys.2022.882973. eCollection 2022.
The mechanisms underpinning ionic transport and barrier function have been relatively well characterised in amphibians and fish. In teleost fish, these processes have mostly been characterised in the gill and intestine. In contrast, these processes remain much less clear for the trunk skin of fish. In this study, we measured barrier function and active transport in the trunk skin of the rainbow trout, using the Ussing chamber technique. The effects of epithelial damage, skin region, salinity, and pharmacological inhibition were tested. Skin barrier function decreased significantly after the infliction of a superficial wound through the removal of scales. Wound healing was already underway after 3 h and, after 24 h, there was no significant difference in barrier function towards ions between the wounded and control skin. In relation to salinity, skin permeability decreased drastically following exposure to freshwater, and increased following exposure to seawater. Changes in epithelial permeability were accompanied by salinity-dependent changes in transepithelial potential and short-circuit current. The results of this study support the idea that barrier function in rainbow trout trunk skin is regulated by tight junctions that rapidly respond to changes in salinity. The changes in transepithelial permeability and short circuit current also suggest the presence of an active transport component. Immunostaining and selective inhibition suggest that one active transport component is an apical V-ATPase. However, further research is required to determine the exact role of this transporter in the context of the trunk skin.
在两栖动物和鱼类中，支撑离子转运和屏障功能的机制已得到较为充分的表征。在硬骨鱼类中，这些过程大多在鳃和肠道中得到了表征。相比之下，鱼类躯干皮肤的这些过程仍不太清楚。在本研究中，我们使用尤斯灌流小室技术测量了虹鳟鱼躯干皮肤的屏障功能和主动转运。测试了上皮损伤、皮肤区域、盐度和药理学抑制的影响。通过去除鳞片造成浅表伤口后，皮肤屏障功能显著下降。3小时后伤口愈合已经开始，24小时后，受伤皮肤和对照皮肤之间对离子的屏障功能没有显著差异。关于盐度，暴露于淡水后皮肤通透性急剧下降，暴露于海水后则增加。上皮通透性的变化伴随着跨上皮电位和短路电流的盐度依赖性变化。本研究结果支持这样一种观点，即虹鳟鱼躯干皮肤的屏障功能由紧密连接调节，紧密连接对盐度变化迅速做出反应。跨上皮通透性和短路电流的变化也表明存在主动转运成分。免疫染色和选择性抑制表明，一种主动转运成分是顶端V-ATP酶。然而，需要进一步研究以确定该转运体在躯干皮肤中的具体作用。
