ABSTRACT
Assuming a glomerular ltration rate of 100 mL/min, the kidneys of an average adult each day lter approximately 150 L of plasma each day, containing approximately 20 mol of sodium (Na+), the equivalent of more than a kilogram of table salt. us, without tubules, we all would have to drink 150 L a day and eat a kilogram of salt to keep up with urinary losses. e enormity of these numbers demonstrates the importance of proper tubular function. Typically, more than 99% of ltered salt and water are reabsorbed. Yet, the tubules not only need to accomplish the massive bulk transport of water and solutes, they also need to nely regulate the precise amount of reabsorption to balance variable intake and extrarenal losses, to maintain volume and electrolyte homoeostasis.
