Please use this identifier to cite or link to this item:
Title: Synaptic vesicle Ca2+/H+ antiport: dependence on the proton electrochemical gradient
Authors: Gonçalves, Paula P. 
Meireles, Sandra M. 
Neves, Paulo 
Vale, M. Graça P. 
Keywords: Ca2+/H+ antiport; Synaptic vesicle; Brain cortex
Issue Date: 1999
Citation: Molecular Brain Research. 71:2 (1999) 178-184
Abstract: Synaptic vesicles isolated from sheep brain cortex accumulate Ca2+ by a mechanism of secondary active transport associated to the H+-pump activity. The process can be visualized either by measuring Ca2+-induced H+ release or [Delta]pH-dependent Ca2+ accumulation. We observed that the amount of Ca2+ taken up by the vesicles increases with the magnitude of the [Delta]pH across the membrane, particularly at Ca2+ concentrations (~500 [mu]M) found optimal for the antiporter activity. Similarly, H+ release induced by Ca2+ increased with the magnitude of [Delta]pH. However, above 60% [Delta]pH (high H+-pump activity), the net H+ release from the vesicles decreased as the pump-mediated H+ influx exceeded the Ca2+-induced H+ efflux. We also observed that the Ca2+/H+ antiport activity depends, essentially, on the [Delta]pH component of the electrochemical gradient (~3 nmol Ca2+ taken up/mg protein), although the [Delta][phi] component may also support some Ca2+ accumulation by the vesicles (~1 nmol/mg protein) in the absence of [Delta]pH. Both Ca2+-induced H+ release and [Delta]pH-dependent Ca2+ uptake could be driven by an artificially imposed proton motive force. Under normal conditions (H+ pump-induced [Delta]pH), the electrochemical gradient dependence of Ca2+ uptake by the vesicles was checked by inhibition of the process with specific inhibitors (bafilomycin A1, ergocryptin, folymicin, DCCD) of the H+-pump activity. These results indicate that synaptic vesicles Ca2+/H+ antiport is indirectly linked to ATP hydrolysis and it is essentially dependent on the chemical component ([Delta]pH) of the electrochemical gradient generated by the H+-pump activity.
DOI: 10.1016/S0169-328X(99)00183-7
Rights: openAccess
Appears in Collections:FCTUC Ciências da Vida - Artigos em Revistas Internacionais

Files in This Item:
File Description SizeFormat
filecafbeab10f764584b7fa3104d95a0d84.pdf321.8 kBAdobe PDFView/Open
Show full item record


checked on Aug 2, 2022

Page view(s) 20

checked on Sep 28, 2022

Download(s) 50

checked on Sep 28, 2022

Google ScholarTM




Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.