A primary fish gill cell culture model to assess pharmaceutical uptake and efflux: Evidence for passive and facilitated transport

• Published in: Aquatic toxicology 2015-02, Vol.159, p.127-137
• Main Authors: Stott, Lucy C., Schnell, Sabine, Hogstrand, Christer, Owen, Stewart F., Bury, Nic R.
• Format: Article
• Language: English
• Subjects: 3Rs; Animal alternatives; Animals; ATP-Binding Cassette Transporters - metabolism; Bio-concentration; Biological Transport - drug effects; Epithelium - metabolism; Fish; Fresh Water; Gills - cytology; Gills - drug effects; Models, Biological; Oncorhynchus mykiss; Oncorhynchus mykiss - physiology; Pharmaceutical Preparations - metabolism; Pharmaceuticals; Propranolol - metabolism; Rainbow trout; Teleostei; Water Pollutants, Chemical - toxicity
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2014.12.007

•An in vitro model of the fish gill can be used to determine pharmaceutical transport across the gill.•Propranolol uptake across this model is concentration and pH dependent and affected by inhibitors.•A component of the uptake of some drugs is via a facilitated process. The gill is the principle site of xenobiotic transfer to and from the aqueous environment. To replace, refine or reduce (3Rs) the large numbers of fish used in in vivo uptake studies an effective in vitro screen is required that mimics the function of the teleost gill. This study uses a rainbow trout (Oncorhynchus mykiss) primary gill cell culture system grown on permeable inserts, which tolerates apical freshwater thus mimicking the intact organ, to assess the uptake and efflux of pharmaceuticals across the gill. Bidirectional transport studies in media of seven pharmaceuticals (propranolol, metoprolol, atenolol, formoterol, terbutaline, ranitidine and imipramine) showed they were transported transcellularly across the epithelium. However, studies conducted in water showed enhanced uptake of propranolol, ranitidine and imipramine. Concentration-equilibrated conditions without a concentration gradient suggested that a proportion of the uptake of propranolol and imipramine is via a carrier-mediated process. Further study using propranolol showed that its transport is pH-dependent and at very low environmentally relevant concentrations (ngL−1), transport deviated from linearity. At higher concentrations, passive uptake dominated. Known inhibitors of drug transport proteins; cimetidine, MK571, cyclosporine A and quinidine inhibited propranolol uptake, whilst amantadine and verapamil were without effect. Together this suggests the involvement of specific members of SLC and ABC drug transporter families in pharmaceutical transport.