Zinc bioaccumulation and ionoregulatory impacts in Fundulus heteroclitus exposed to sublethal waterborne zinc at different salinities

• Published in: Comparative biochemistry and physiology. Toxicology & pharmacology 2014-11, Vol.166, p.96-104
• Main Authors: Loro, Vania Lucia, Nogueira, Lygia, Nadella, Sunita R., Wood, Chris M.
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - chemistry; Adenosine Triphosphatases - metabolism; Animals; Atlantic Ocean; Ca2 + ATPase; Calcium homeostasis; Dose-Response Relationship, Drug; Environmental Exposure - adverse effects; Female; Fish Diseases - blood; Fish Diseases - chemically induced; Fish Diseases - metabolism; Fish Diseases - prevention & control; Fish Proteins - agonists; Fish Proteins - antagonists & inhibitors; Fish Proteins - metabolism; Fundulidae; Gills - chemistry; Gills - drug effects; Gills - metabolism; Hormesis; Intestines - chemistry; Intestines - drug effects; Intestines - metabolism; Killifish; Lethal Dose 50; Liver - chemistry; Liver - drug effects; Liver - metabolism; Male; Na+,K+ ATPase; New Hampshire; Salinity; Sodium homeostasis; Tissue Distribution; Toxicity Tests, Acute; Water Pollutants, Chemical - administration & dosage; Water Pollutants, Chemical - blood; Water Pollutants, Chemical - pharmacokinetics; Water Pollutants, Chemical - toxicity; Water-Electrolyte Imbalance - chemically induced; Water-Electrolyte Imbalance - metabolism; Water-Electrolyte Imbalance - prevention & control; Water-Electrolyte Imbalance - veterinary; Zinc; Zinc - administration & dosage; Zinc - blood; Zinc - pharmacokinetics; Zinc - toxicity
• ISSN: 1532-0456; 1878-1659
• DOI: 10.1016/j.cbpc.2014.07.004

Exposure of Fundulus heteroclitus to an environmentally relevant Zn concentration (500μgL−1) at different salinities (0, 3.5, 10.5, and 35ppt) revealed the following effects: (i) plasma [Zn] doubled after exposure at 0ppt, a response which was eliminated at 35 ppt. Tissue [Zn] also increased in gill, liver, intestine, and carcass at 0ppt. (ii) Both branchial and intestinal Ca2+ ATPase activities decreased in response to Zn at 0ppt and were elevated at 35 ppt. Plasma [Ca] decreased by 50% at 0ppt and by 30% at 3.5ppt and increased by 20% at 35ppt. Gill [Ca] decreased by 35% at 0ppt and increased by about 30% at all higher salinities. (iii) Branchial Na+,K+ ATPase activity decreased by 50% at 0ppt, increased by 30% and 90% at 10.5 and 35ppt respectively. Intestinal Na+,K+ ATPase activity was reduced by 30% at 0ppt. (iv) Plasma [Na] decreased by 30% at 0ppt in Zn-exposed. Zn exposure also disturbed the homeostasis of tissue cations (Na+, K+, Ca++, Mg++) in a tissue-specific and salinity-dependent manner. (v) Drinking rate was not altered by Zn exposure. In toxicity tests, acute Zn lethality (96-h LC50) increased in a close to linear fashion from 9.8mg L−1 at 0ppt to 75.0mgL−1 at 35ppt. We conclude that sublethal Zn exposure causes pathological changes in both Ca++ and Na+ homeostases, and that increasing salinity exerts protective effects against both sublethal and lethal Zn toxicities.