Sweat
Low sweat production (rest, cool temperature) - Cells in the straight duct reabsorb most of the sodium and chlorine from the fluid. This happens because there is enough time for reabsorption. In addition, water is reabsorbed osmotically. So not much sweat reaches the outside. Also, the composition of this sweat is significantly different from the primary secretion. There is not as much sodium and chloride, and there is more potassium.