G. Kubikdobosz et al., THE EFFECT OF INHIBITORS OF PLASMA-MEMBRANE H-ATPASE AND OXIDOREDUCTASES ON NH4+ UPTAKE BY PISUM ARVENSE ROOTS(), Acta Societatis Botanicorum Poloniae, 63(3-4), 1994, pp. 287-292
The effect of inhibitors of plasma membrane oxidoreductases (quinacrin
e and dicumarol) and H+-ATPase (dicyclohexylcarbodiimide and orthovana
date) on ammonium uptake by Pisum arvense seedlings and the activities
of H+-ATPase and NADH-ferricyanide oxidoreductase was investigated. T
he uptake solution contained 50 mu M NH4+. In 1 h experiments, quinacr
ine and dicumarol depressed strongly and irreversibly the rate of NH4 uptake and markedly inhibited the activity of NADH-ferricyanide oxido
reductase in the plasma membrane vesicles prepared from root cells. Si
multaneously, sodium orthovanadate inhibited the activity of plasma me
mbrane H+-ATPase increased the rate of NH4+ uptake. Dicyclohexylcarbod
iimide 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 mu M NH4+ and H+-ATPase activity,
and suggest that membrane redox systems play a predominant role in th
is process.