Control of transport by epithelia

硬骨鱼利用鳃、肠、肾和膀胱的活性离子和水运输机制进行渗透调节。这些上皮结构包含具有调控转运蛋白的特化上皮转运细胞。我们研究了这些转运体在天然上皮中的原位调控，特别是在硬骨鱼鳃和相关渗透调节器官的富含线粒体氯化物的细胞中作为我们的生理模型系统。强碱性硬骨鱼的离子分泌受到激素、神经递质和血液渗透水平的迅速调节。当鱼从海水转移到淡水时，它们的血液会被稀释；这种短暂的渗透压下降迅速而可逆地抑制了通常存在于海水中的盐（NaCl）的分泌。反过来，这种效应有助于动物在淡水中保留盐分。这种效应是一种直接的细胞水平调节，由离子转运细胞感知渗透压的变化。相反，当鱼进入高盐环境时，血液浓度会刺激盐的分泌。此外，这些细胞还经历补偿来调节细胞体积。这一机制涉及一系列调节蛋白、蛋白激酶和磷酸酶，它们分别激活或灭活膜结合离子转运体。该研究对比较生理学、比较内分泌学、渔业和水产养殖具有重要意义。此外，由于阴离子通道“囊性纤维化跨膜传导调节剂”（CFTR）在该系统中运输盐，因此研究鱼类CFTR调控可能对发现CFTR调控和发现囊性纤维化的潜在原因具有重要意义。

Teleost fish osmoregulate using active ion and water transport mechanisms of the gills, intestine, kidney and urinary bladder. These epithelial structures contain specialized epithelial transport cells with regulated transport proteins. We study regulation of these transporters in situ in the native epithelium, particularly in mitochondria rich chloride cells of the teleost gill and related osmoregulatory organs as our physiological model system. The ion secretion by hardy euryhaline teleosts such as the killifish Fundulus heteroclitus is rapidly regulated by hormones, neurotransmitters and by the osmotic level of the blood. When fish move from seawater to fresh water, their blood becomes diluted; this transient decrease in osmolality rapidly and reversibly inhibits the salt (NaCl) secretion that is normally present in seawater. In turn, the effect helps the animal retain salt while in fresh water. The effect is a direct cell level regulation by ion transportng cells that sense changes in osmolality. Conversely, blood concentration, such as occurs when the fish enter hypersaline environments stimulates saltsecretion. In addition, these cells also undergo compensation to regulate cell volume. The mechanism involves a series of regulatory proteins, protein kinases and phosphatases that activate or deactivate (respectively) the membrane-bound ion transporters. The research is important to comparative physiology, comparative endocrinology, fisheries and aquaculture. Also, because the anion channel "Cystic Fibrosis Transmembrane conductance Regulator" (CFTR) transports salt in this system, studies of CFTR regulation in fish may be important to discovery of CFTR regulation and important to discovering underlying causes of Cystic Fibrosis.