The effect of inhibitors of plasma membrane H+ - ATPase and oxidoreductases on NH4+ uptake by Pisum arvense roots
Genowefa Kubik-Dobosz, Aleksandra Turska, Halina Lekacz, Waldemar Karcz, Józef Buczek
Abstract
The effect of inhibitors of plasma membrane oxidoreductases (quinacrine and dicumarol) and H+-ATPase (dicyclohexylcarbodiimide and orthovanadate) on ammonium uptake by Pisum arvense seedlings and the activities of H+-ATPase and NADH-ferricyanide oxidoreductase was investigated. The uptake solution contained 50 µM NH4+. In I h experiments, quinacrine and dicumarol depressed strongly and irreversibly the rate of NH4+ uptake and markedly inhibited the activity of NADH-ferri-cyanide oxidoreductase in the plasma membrane vesicles prepared from root cells. Simultaneously, sodium orthovanadate inhibited the activity of plasma membrane H+-ATPase increased the rate of NH4+ uptake. Dicyclohexylcarbodiimide inhibited H+-ATPase activity and increased efflux of NH4+ from roots to ambient solution. The results indicate on the lack of direct connection between uptake rate of 50 µM NH4+ and H+-ATPase activity, and suggest that membrane redox systems play a predominant role in this process.
Keywords
ammonium; uptake; inhibitors; oxidoreductase NADH-ferricyanide; H+ - ATPase
DOI:
https://doi.org/10.5586/asbp.1994.039
Journal ISSN:- 2083-9480 (online)
- 0001-6977 (print; ceased since 2016)
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