Here, I show the paracellular movement of calcium in the proximal tubule. Up to 65% of the calcium is reabsorbed at this level. The paracellular (around the cells) movement of calcium could be through solvent drag (the majority), which follows the movement of sodium and water. There is another mechanism that uses a change in transepithelial voltage (paracellular diffusion) to favor the reabsorption of calcium around (not through) the tubular cells.
