The molecular and cellular physiology of basolateral organic anion transport in mammalian renal tubules

William H. Dantzler, Stephen H. Wright

Research output: Contribution to journalArticlepeer-review

70 Scopus citations


Basolateral transport of organic anions (OAs) into mammalian renal proximal tubule cells is a tertiary active transport process. The final step in this process involves movement of OA into the cells against its electrochemical gradient in exchange for α-ketoglutarate (αKG) moving down its electrochemical gradient. Two homologous transport proteins (OAT1 and OAT3) that function as basolateral OA/αKG exchangers have been cloned and sequenced. We are in the process of determining the functional distribution and regulation of OAT1 and OAT3 in renal tubules. We are using rabbit OAT1 (rbOAT1) and OAT3 (rbOAT3) expressed in heterologous cell systems to determine substrate specificity and putative regulatory steps and isolated rabbit proximal renal tubule segments to determine functional distribution and physiological regulation of these transporters within their native epithelium. Rabbit OAT1 and OAT3 differ distinctly in substrate specificity. For example, rbOAT1 has a high affinity for the classical renal OA transport substrate, p-aminohippurate (PAH), whereas rbOAT3 has no affinity for PAH. In contrast, rbOAT3 has a high affinity for estrone sulfate (ES), whereas rbOAT1 has only a very slight affinity for ES. Both rbOAT1 and rbOAT3 appear to have about the same affinity for fluorescein (FL). These differences and similarities in substrate affinities make it possible to functionally map transporters along the renal tubules. Initial data indicate that OAT1 predominates in S2 segments of the rabbit proximal tubules, but studies of other segments are just beginning. Transport of a given substrate in any tubule segment depends on both the affinity of each transporter which can accept that substrate as well as the level of expression of each of those processes in that particular tubule segment. Basolateral PAH transport (presumably OAT1 activity) appears to be down-regulated by activation of protein kinase C (PKC) and up-regulated via mitogen-activated protein kinase (MAPK) through phospholipase A2 (PLA2), prostaglandin E2 (PGE2), cyclic AMP, and protein kinase A (PKA) activation.

Original languageEnglish (US)
Pages (from-to)185-193
Number of pages9
JournalBiochimica et Biophysica Acta - Biomembranes
Issue number2
StatePublished - Dec 30 2003


  • Basolateral transport
  • OAT1
  • OAT3
  • Organic anion
  • Renal tubule

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology


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