title: Branchial versus intestinal silver toxicity and uptake in the marine teleost Parophrys vetulus.
abstract: Exposure to elevated waterborne silver as AgNO3 (4.07 microM=448 microg l(-1)) in seawater resulted in osmoregulatory disturbance in the lemon sole (Parophrys vetulus). The main effects were increased plasma Na+ and Cl- concentrations which translated into increased plasma osmolality. Plasma Mg2+ levels were also slightly increased after 96 h exposure. Using radioisotopic flux measurements, a 50% reduction in branchial unidirectional Na+ extrusion was observed after 48 h silver exposure. By applying an intestinal perfusion approach, we were able to separate and thus quantify the intestinal contribution to the observed silver-induced physiological disturbance and internal silver accumulation. This analysis revealed that the intestinal contribution to silver-induced ionoregulatory toxicity was as high as 50-60%. In marked contrast, internal silver accumulation (in liver and kidney) was found to be derived exclusively from uptake across the gills. Drinking of silver-contaminated seawater resulted in substantial silver accumulation in the intestinal tissue (but apparently not silver uptake across the intestine), which probably explains the intestinal contribution to silver-induced physiological disturbance.
authors.affiliation: Bamfield Marine Station, British Columbia, Canada. grosellm@mcmaster.ca
authors.forename: M
authors.initials: M
authors.lastname: Grosell
authors.forename: C M
authors.initials: CM
authors.lastname: Wood
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000097:blood; D002118:Calcium / Q000097:blood; D002245:Carbon Dioxide / Q000097:blood; D002712:Chlorides / Q000097:blood; D005412:Flatfishes / Q000502:physiology*; D006400:Hematocrit; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000378:metabolism; D008274:Magnesium / Q000097:blood; D018482:Muscle, Skeletal / Q000378:metabolism; D012835:Silver Nitrate / Q000493:pharmacokinetics* / Q000633:toxicity*; D012964:Sodium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014018:Tissue Distribution; D014867:Water / Q000378:metabolism; D014873:Water Pollutants / Q000493:pharmacokinetics / Q000633:toxicity; D014882:Water-Electrolyte Balance / Q000187:drug effects*
chemical_list: D001639:Bicarbonates; D002712:Chlorides; D014873:Water Pollutants; D014867:Water; D002245:Carbon Dioxide; D012835:Silver Nitrate; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D002118:Calcium