Perry S F
Department of Biology, University of Ottawa, Ontario, Canada.
Annu Rev Physiol. 1997;59:325-47. doi: 10.1146/annurev.physiol.59.1.325.
This review focuses on the structure and function of the branchial chloride cell in freshwater fishes. The mitochondria-rich chloride cell is believed to be the principal site of trans-epithelial Ca2+ and Cl- influxes. Though currently debated, there is accruing evidence that the pavement cell is the site of Na+ uptake via channels linked electrically to an apical membrane vacuolar H(+)-ATPase (proton pump). Chloride cells perform an integral role in acid-base regulation. During conditions of alkalosis, the surface area of exposed chloride cells is increased, which serves to enhance base equivalent excretion as the rate of Cl-/HCO3- exchange is increased. Conversely, during acidosis, the chloride cell surface area is diminished by an expansion of the adjacent pavement cells. This response reduces the number of functional Cl-/HCO3- exchangers. Under certain conditions that challenge ion regulation, chloride cells proliferate on the lamellae. This response, while optimizing the Ca2+ and Cl- transport capacity of the gill, causes a thickening of the blood-to-water diffusion barrier and thus impedes respiratory gas transfer.
本综述聚焦于淡水鱼鳃部氯化物细胞的结构与功能。富含线粒体的氯化物细胞被认为是跨上皮钙离子和氯离子内流的主要部位。尽管目前仍存在争议，但越来越多的证据表明，扁平细胞是通过与顶端膜液泡H(+)-ATP酶（质子泵）电连接的通道进行钠离子摄取的部位。氯化物细胞在酸碱调节中发挥着不可或缺的作用。在碱中毒情况下，暴露的氯化物细胞表面积增加，随着Cl-/HCO3-交换速率的提高，这有助于增强碱当量的排泄。相反，在酸中毒时，相邻扁平细胞的扩张会使氯化物细胞表面积减小。这种反应会减少功能性Cl-/HCO3-交换体的数量。在某些挑战离子调节的条件下，氯化物细胞会在鳃小片上增殖。这种反应虽然优化了鳃对钙离子和氯离子的运输能力，但会导致血液与水之间的扩散屏障增厚，从而阻碍呼吸气体的交换。
