Production of superoxides and nitric oxide generation in haemocytes of mussel Mytilus galloprovincialis (Lmk.) after exposure to cadmium: a possible involvement of Na(+)/H(+) exchanger in the induction of cadmium toxic effects.
The present study investigates cadmium (Cd) ability to enhance superoxides (O(2-)) and nitric oxide (NO) production (as nitrites) in haemocytes of mussel Mytilus galloprovincialis as well as the possible involvement of Na(+)/H(+) exchanger (NHE) in the induction of NADPH oxidase and NO synthase activity. PMA, a well-known PKC-mediated NADPH oxidase as well as NO synthase stimulator was also used, in order to verify Cd effects on both O(2-) and NO generation. According to the results of the present study, micromolar concentrations of Cd (0.05, 5, 10 and 50 microM) seemed to enhance O(2-) and NO generation in haemocytes of mussels. Moreover, O(2-) and NO generation in haemocytes exposed to Cd could be enhanced by its ability to induce reactive oxygen species (ROS) but respiratory burst activation as well. Inhibition of NO synthase with 10 microM l-NAME, significantly attenuated Cd ability to enhance O(2-) production and diminished NO generation, thus leading to the suggestion that Cd toxic effects, started at concentration of 50 muM, could enhance NADPH oxidase and NO synthase stimulation in haemocytes of mussels. NHE seems to play a regulatory role in the induction of either O(2-) or NO generation in haemocytes exposed to the metal, since its inhibition with the use of 10 microM EIPA significantly decrease both O(2-) and NO production. The involvement of NHE in the induction of O(2-) and NO generation, probably via PKC-mediated NADPH oxidase and NO synthase activation, is likely to be crucial to haemocytes exposed to heavy metals, such as Cd.
Dailianis
Stefanos
S
Section of Animal Biology, Department of Biology, Faculty of Sciences, University of Patras, Patras 26 500, Greece. sdailianis@upatras.gr
D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D004781:Environmental Exposure; D005786:Gene Expression Regulation / Q000187:drug effects; D006434:Hemocytes / Q000187:drug effects; D049878:Mytilus / Q000187:drug effects* / Q000378:metabolism; D009499:Neutral Red / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D009573:Nitrites; D017923:Sodium-Hydrogen Exchangers; D014874:Water Pollutants, Chemical; D002104:Cadmium; D013481:Superoxides; D009499:Neutral Red; D009569:Nitric Oxide