In vitro dose dependent inverse effect of nantenine on synaptosomal membrane K+-p-NPPase activity

In vitro dose dependent inverse effect of nantenine on synaptosomal membrane K+-p-NPPase activity

Author Ribeiro, Rosana de Alencar Autor UNIFESP Google Scholar
Arnaiz, Georgina Rodriguez de Lores Google Scholar
Institution Univ Buenos Aires
Universidade Federal de São Paulo (UNIFESP)
Abstract The effect of nantenine, an aporphine alkaloid, on ATPase K+-dependent dephosphorylation was evaluated using p-nitrophenylphosphate (p-NPP) as substrate. Basal K+-p-NPPase activity was significantly increased with 3 x 10(-4) M, remained unchanged with 3 x 10(-6) M, 3 x 10(-5) M but was reduced with 7.5 x 10(-4) M and 1 x 10(-3) M nantenine, whereas Mg2+-p-NPPase activity was not modified, Kinetic studies showed that K+-p-NPPase inhibition by nantenine is competitive to KCl but non-competitive to substrate p-NPP, whereas K+-p-NPPase stimulation by nantenine is non-competitive to KCl but competitive to p-NPP. These data suggest that there may be two acceptor sites for nantenine in p-NPPase, one eliciting stimulation and the other inhibition of K+-dependent p-NPP hydrolysis. Considering the biphasic action of nantenine on seizures and the correlation between decreased ATPase activity and seizure development, alkaloid anticonvulsant effect observed at low nantenine doses is attributable to the stimulation of phosphatase activity whereas the convulsant effect at high alkaloid doses seems related to Na+, K+-ATPase inhibition.
Keywords nantenine
in vitro dose dependent inverse effect
synaptosomal membrane
Language English
Date 2001-03-01
Published in Phytomedicine. Jena: Urban & Fischer Verlag, v. 8, n. 2, p. 107-111, 2001.
ISSN 0944-7113 (Sherpa/Romeo, impact factor)
Publisher Urban & Fischer Verlag
Extent 107-111
Access rights Closed access
Type Article
Web of Science ID WOS:000168193100005

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