Proximal tubule (of the kidney)

The **proximal tubule** is the first tubular segment of the nephron in the kidney, arising from the Bowman’s capsule and extending to the loop of Henle. It is subdivided into the proximal convoluted tubule and proximal straight tubule, and can be further dissected into segments S1, S2, and S3 based on ultrastructure[1][7]. Its epithelial cells are highly specialized for active and passive reabsorption of most filtered water, glucose, amino acids, electrolytes, and proteins, and for secretion of selected metabolic wastes. The cells are characterized by a prominent brush border, large numbers of mitochondria, and extensive membrane specializations for solute transport[1][3]. Damage or dysfunction in the proximal tubule underlies various kidney diseases including acute kidney injury and chronic kidney disease[5]. The tissue’s unique transporters are sometimes targeted or affected by drugs, especially nephrotoxic compounds, although the term "proximal tubule" itself does not refer to a single molecular target[2][8].

Other names

Proximal convoluted tubulePCTPars convolutaProximal straight tubulePSTPars recta

Not directly applicable; however, drugs may act by inhibiting or modulating solute transporters (e.g., SGLT2 for glucose) or by inducing nephrotoxicity through cellular injury in proximal tubule epithelial cells (e.g., cisplatin, aminoglycosides).