Effect of plasmalemma ATPase inhibitors, diethylstilbestrol and orthovanadate, on fusicoccin-induced H+ extrusion in maize roots

Colombo, R.; Bonetti, A.; Cerana, R.; Lado, P. . Ist. di Scienze Botaniche

Effect of plasmalemma ATPase inhibitors, diethylstilbestrol and orthovanadate, on fusicoccin-induced H+ extrusion in maize roots

1981

Colombo, R. | Bonetti, A. | Cerana, R. | Lado, P. (Milan Univ. (Italy). Ist. di Scienze Botaniche)

In order to investigate the possibility that fusicoccin(FC)-induced eletrogenic H+ extrusion and K+ uptake in higher plants depend on the activity of a plasmalemma ATPase, we have studied the effect of two NON-mitochondrial membrane-bound ATPase inhibitors, diethylstilbestrol (DES) and vanadate, on the transport of H+ and K+ in maize root segments. Both DES and vandate strongly inhibited the stimulating effect of FC on H+ extrusion and K+ uptake. Furthermore, vanadate inhibited the FC-induced H+ extrusion in the presence of a lipophilic cation, tributylbenzyle-ammonium (TBBA+), and in the absence of K+. The parallel determination of ATP and pyruvate levels showed that in our experimental conditions the inhibiting effect of the substances on transport did not seem to depend on an effect on energy metabolism. The results of this paper seem consistent with the view that FC-stimulated H+ extrusion and K+ uptake depend on the activation of a plasmalemma ATPase, catalyzing an electrogenic H+ uniport, electrically coupled with K+ influx.

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