Novel method for kinetic analysis applied to transport by the uniporter OCT2

Research output: Contribution to journalArticlepeer-review


The kinetics of solute transport shed light on the roles these processes play in cellular physiology, and the absolute values of the kinetic parameters that quantitatively describe transport are increasingly used to model its impact on drug clearance. However, accurate assessment of transport kinetics is challenging. Although most carrier-mediated transport is adequately described by the Michaelis–Menten equation, its use presupposes that the rates of uptake used in the analysis of maximal rates of transport (Jmax) and half-saturation constants (Kt) reflect true unidirectional rates of influx from known concentrations of substrate. Most experimental protocols estimate the initial rate of transport from net substrate accumulation determined at a single time point (typically between 0.5 and 5 min) and assume it reflects unidirectional influx. However, this approach generally results in systematic underestimates of Jmax and overestimates of Kt; the former primarily due to the unaccounted impact of efflux of accumulated substrate, and the latter due to the influence of unstirred water layers. Here, we describe the bases of these time-dependent effects and introduce a computational model that analyzes the time course of net substrate uptake at several concentrations to calculate Jmax and Kt for unidirectional influx, taking into account the influence of unstirred water layers and mediated efflux. This method was then applied to calculate the kinetics of transport of 1-methyl-4-phenylpryridinium and metformin by renal organic cation transporter 2 as expressed in cultured Chinese hamster ovary cells.

Original languageEnglish (US)
Pages (from-to)F370-F387
JournalAmerican Journal of Physiology - Renal Physiology
Issue number3
StatePublished - Sep 2022


  • kinetics
  • model
  • organic cation
  • proximal tubule
  • transport

ASJC Scopus subject areas

  • Physiology
  • Urology


Dive into the research topics of 'Novel method for kinetic analysis applied to transport by the uniporter OCT2'. Together they form a unique fingerprint.

Cite this