title: Organic Cation Transporter 2 Overexpression May Confer an Increased Risk of Gentamicin-Induced Nephrotoxicity.
abstract: Nephrotoxicity is a relevant limitation of gentamicin, and obese patients have an increased risk for gentamicin-induced kidney injury. This damage is thought to depend on the accumulation of the drug in the renal cortex. Obese rats showed substantially higher levels of gentamicin in the kidney than did lean animals. This study characterized the role of organic cation transporters (OCTs) in gentamicin transport and elucidated their possible contribution in the increased renal accumulation of gentamicin in obesity. The mRNA and protein expression levels of the organic cation transporters Oct2 (Slc22a2) and Oct3 (Slc22a3) were increased in kidney samples from obese mice fed a high-fat diet. Similarly, OCT2 (∼2-fold) and OCT3 (∼3-fold) showed increased protein expression in the kidneys of obese patients compared with those of nonobese individuals. Using HEK293 cells overexpressing the different OCTs, human OCT2 was found to transport [(3)H]gentamicin with unique sigmoidal kinetics typical of homotropic positive cooperativity (autoactivation). In mouse primary proximal tubular cells, [(3)H]gentamicin uptake was reduced by approximately 40% when the cells were coincubated with the OCT2 substrate metformin. The basolateral localization of OCT2 suggests that gentamicin can enter proximal tubular cells from the blood side, probably as part of a slow tubular secretion process that may influence intracellular drug concentrations and exposure time. Increased expression of OCT2 may explain the higher accumulation of gentamicin, thereby conferring an increased risk of renal toxicity in obese patients.
authors.affiliation: Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Zhibo
authors.initials: Z
authors.lastname: Gai
authors.affiliation: Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Michele
authors.initials: M
authors.lastname: Visentin
authors.affiliation: Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Hiller
authors.affiliation: Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Evelin
authors.initials: E
authors.lastname: Krajnc
authors.affiliation: Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Tongzhou
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Pathology, School of Medicine, Shandong University, Jinan, China.
authors.forename: Junhui
authors.initials: J
authors.lastname: Zhen
authors.affiliation: Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, Zurich, Switzerland gerd.kullak@usz.ch.
authors.forename: Gerd A
authors.initials: GA
authors.lastname: Kullak-Ublick
mesh_terms: D000818:Animals; D002460:Cell Line; D059305:Diet, High-Fat; D005260:Female; D005839:Gentamicins / Q000009:adverse effects* / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism*; D007674:Kidney Diseases / Q000139:chemically induced* / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008687:Metformin / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism; D027701:Organic Cation Transport Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D005839:Gentamicins; D027701:Organic Cation Transport Proteins; D012333:RNA, Messenger; D008687:Metformin