Cell Volume Regulation and Taurine Transport in Fish

所有细胞必须保持相对恒定的体积才能正常工作。PI将使用鱼类来研究细胞体积调节，因为它们是研究这一过程的优秀对象。当海洋鱼类从海水中进入微咸水时，由于环境更稀，它们的体液会被稀释。为了避免细胞膨胀，它们将离子和小的有机分子从细胞中排出，从而平衡细胞内外的渗透压（盐的浓度）。一种非必需氨基酸，牛磺酸，是这种调节机制的主要组成部分。随着细胞外液的稀释，牛磺酸从细胞释放到血液中，然后必须从体内排出。由于它不能被代谢，所以必须由肾脏排出体外。PI已经表明，海鱼通过一个依赖钠离子和部分依赖氯离子的运输系统分泌这种化合物穿过肾小管细胞。哺乳动物的肾脏似乎也有类似的运输系统，但方向相反；牛磺酸被肾脏重新吸收。在这个项目中，PI打算进一步描述这种运输系统并研究其调节机制。在这些研究中获得的信息应该增加对细胞在面对细胞外液浓度变化时如何调节其体积的理解。

All cells must maintain a relatively constant volume in order to function properly. The PI will use fish to study cell volume regulation since they are excellent subjects in which to study this process. When marine fish move into brackish water from sea water they are confronted with a dilution of their body fluids because of the more dilute environment. To avoid a resultant swelling of their cells they unload ions and small organic molecules from their cells and thus balance the osmolarity (concentration of salts) between the inside and outside of their cells. A non-essential amino acid, taurine, is a prime component of this regulatory mechanism. Following dilution of the extracellular fluid taurine is released from the cells into the blood and must then be eliminated from the body. As it is not metabolised it must be excreted by the kidneys. The PI has shown that the marine fish secrete this compound across the kidney tubule cell by a transport system that is dependent on sodium ion and partially dependent on chloride ion. The mammalian kidney appears to have a similar transport system but it moves in the opposite direction; taurine is reabsorbed by the kidney. In this project the PI intends to further characterize this transport system and study its regulatory mechanisms. The information gained in these studies should increase understanding of how cells regulate their volume when confronted by changes in the concentration of the extracellular fluids.