The proximal convoluted tubule is the first and longest coiled segment of the nephron after the glomerular capsule. Its cells have a dense brush border of microvilli and many mitochondria. It reabsorbs about two thirds of the filtered salt and water and nearly all filtered glucose and amino acids.
| Location | Renal cortex, near its renal corpuscle |
|---|---|
| Parts |
|
| Blood Supply | Peritubular capillaries (from efferent arterioles) |
| Venous drainage |
|
Reabsorbs most filtered water, sodium, bicarbonate, glucose and amino acids, and secretes organic acids, bases and many drugs into the urine.
Because it is so metabolically active, the proximal tubule is the part most often injured by low blood flow and by toxins such as aminoglycoside antibiotics and some chemotherapy drugs. Generalised failure of proximal reabsorption is called Fanconi syndrome. SGLT2 inhibitor drugs act here to block glucose reabsorption.
Widespread failure of proximal tubular reabsorption, so glucose, amino acids, phosphate and bicarbonate are lost in the urine.
Death of tubular cells from ischaemia or toxins, causing sudden kidney failure.
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