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Determination of Energy Requirements for P‐glycoprotein Function in Eastern Oysters, Crassostrea virginica
Author(s) -
Reynolds Kristen Nicole,
Sokolova Inna
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.757.23
Subject(s) - verapamil , crassostrea , p glycoprotein , gill , biology , chemistry , ostreidae , oyster , pharmacology , biochemistry , shellfish , aquatic animal , ecology , calcium , fishery , antibiotics , multiple drug resistance , fish <actinopterygii> , organic chemistry
Cadmium (Cd) is an important pollutant in aquatic habitats, and Cd exposure results in increased energy demand in oysters Crassostrea virginica . However, mechanisms of this increase are not well understood. To determine whether activity of ATP‐dependent multixenobiotic resistance pumps (P‐glycoproteins, or P‐gp) contributes to higher metabolic rate in Cd‐exposed oysters, we measured oxygen consumption and P‐gp substrate (calcein‐AM) uptake in the presence and absence of specific P‐gp inhibitors (verapamil, cyclosporin A and JS‐2190) in isolated gills from control and Cd‐exposed (50 μg L −1 , 30–70 days) oysters. Lowest effective concentrations of inhibitors (66.7 μM verapamil, 13.3 μM cyclosporin A and 16.7 μM JS‐2190) were selected in dose‐response experiments. In control oysters, addition of P‐gp inhibitors had no effect on calcein‐AM uptake indicating low P‐gP activity, whereas in Cd‐exposed oysters inhibition of P‐gp‐mediated efflux led to a significant increase of calcein accumulation by 50–100%. Respiration of isolated gills was decreased by 4–10% by P‐gp inhibitors; however, this decrease was statistically not significant indicating that contribution of P‐gp activity to energy balance was negligible in control and Cd‐exposed oysters. Supported by United Negro College Fund, Undergraduate Summer Research Fellowship of the American Physiological Society and NSF CAREER (IBN‐0347238).