Early steps in the oxidative burst induced by cadmium in cultured tobacco cells (BY-2 line).
The rapid generation of H(2)O(2) by Cd(2+)-treated plant cells was investigated in cultured tobacco (Nicotiana tabacum L.) BY-2 cells. The starting point for the generation of H(2)O(2) has been located at the cell plasma membrane using cytochemical methods. Treatment of the cells with diphenyleneiodonium (DPI) and imidazol, both inhibitors of the neutrophil NADPH oxidase, prevented the generation of H(2)O(2) induced by Cd(2+). These data suggest the involvement of an NADPH oxidase-like enzyme leading to H(2)O(2) production through O(2)(*-) dismutation by superoxide dismutase enzymes. To investigate the implication of Ca(2+) channels in a Cd(2+)-induced oxidative burst, different inhibitors of Ca(2+) channels were used. Only La(3+) totally inhibited the generation of H(2)O(2) induced by Cd(2+). However, verapamil and nifedipine, inhibitors of Ca(2+) channels, were not effective. Calmodulin or a Ca(2+)-dependent protein kinase is also implicated in the signal transduction sequence, based on the results obtained with two types of calmodulin antagonists, fluphenazine and N-(-6-amino-hexyl)-5-chloro-1-naphthalenesulphonamide (W-7) and staurosporine, an inhibitor of protein kinases. However, neomycin, an inhibitor of the phosphoinositide cycle, did not inhibit the generation of H(2)O(2) induced by Cd(2+), suggesting mainly an induction of the oxidative burst mediated by calmodulin and/or calmodulin-dependent proteins.
Olmos
Enrique
E
Departamento de Nutrición y Fisiología Vegetal, CEBAS-CSIC, PO Box 4195, 30080 Murcia, Spain.
Martínez-Solano
Juan R
JR
Piqueras
Abel
A
Hellín
Eladio
E
D000975:Antioxidants / Q000378:metabolism; D002104:Cadmium / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival; D006861:Hydrogen Peroxide / Q000378:metabolism; D019255:NADPH Oxidases / Q000378:metabolism; D016897:Respiratory Burst / Q000187:drug effects; D015398:Signal Transduction; D014026:Nicotiana / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*
D000975:Antioxidants; D002121:Calcium Channel Blockers; D002104:Cadmium; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; D002118:Calcium