Sodium ions pumped out of the cells into blood against concentration gradient using ATP, so sodium ions will diffuse into PCT cells through sodium co transport from the filtrate down concentration gradient, glucose and amino acids enter PCT by secondary active transport, glucose, amino acids, vitamins, and hormones are reabsorbed completely by active transport, some sodium ions can also be reabsorbed by active transport, chloride ions can also leave by diffusion, the co transport of solutes into the cytoplasm of epithelial cells increase concentration of the cytoplasm, so water moves by osmosis down water potential gradient from filtrate in the PCT lumen into the epithelial cell cytoplasm through the epithelial cell membrane, which in turn enters the blood by osmosis