Unstirred Water Layers and the Kinetics of Organic Cation Transport

Takahiro Shibayama, Mark Morales, Xiaohong Zhang, Lucy J. Martínez-Guerrero, Alfred Berteloot, Timothy W. Secomb, Stephen H. Wright

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Abstract Purpose: Unstirred water layers (UWLs) present an unavoidable complication to the measurement of transport kinetics in cultured cells, and the high rates of transport achieved by overexpressing heterologous transporters exacerbate the UWL effect. This study examined the correlation between measured Jmax and Kt values and the effect of manipulating UWL thickness or transport Jmax on the accuracy of experimentally determined kinetics of the multidrug transporters, OCT2 and MATE1. Methods: Transport of TEA and MPP was measured in CHO cells that stably expressed human OCT2 or MATE1. UWL thickness was manipulated by vigorous reciprocal shaking. Several methods were used to manipulate maximal transport rates. Results: Vigorous stirring stimulated uptake of OCT2-mediated transport by decreasing apparent Kt (Ktapp) values. Systematic reduction in transport rates was correlated with reduction in Ktapp values. The slope of these relationships indicated a 1500Â

Original languageEnglish (US)
Article number1675
Pages (from-to)2937-2949
Number of pages13
JournalPharmaceutical Research
Issue number9
StatePublished - Sep 8 2015


  • kinetics
  • organic cation
  • transport
  • unstirred water layers

ASJC Scopus subject areas

  • Biotechnology
  • Molecular Medicine
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry
  • Pharmacology (medical)


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