Modulation of Ca channels by activation of adenosine A1 receptors in rat striatal glutamatergic nerve terminals |
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Authors: | Antó nio F. Ambró sio,Joã o O. Malva,Arsé lio P. Carvalho,Caetana M. Carvalho |
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Affiliation: | a Center for Neuroscience of Coimbra, Department of Zoology and Faculty of Medicine, University of Coimbra, Coimbra, Portugal b Department of Biology, University of Minho, Braga, Portugal |
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Abstract: | We determined that activation of adenosine A1 receptors in striatal synaptosomes with 100 nM N6-cyclopentyladenosine (CPA) inhibited both the release of endogenous glutamate and the increase of intracellular free Ca2+ concentration ([Ca2+]i), due to 4-aminopyridine (4-AP) stimulation, by 28 and 19%, respectively. Furthermore, CPA enhanced the inhibition of endogenous glutamate release due to ω-conotoxin GVIA (ω-Cgtx GVIA), ω-Cgtx MVIIC or ω-Cgtx GVIA plus ω-Cgtx MVIIC. Similar effects were observed in the [Ca2+]i signal. The inhibitory effects of CPA and ω-Cgtx GVIA were additive, but the effects of CPA and ω-Cgtx MVIIC were only partially additive. These results suggest that P/Q-type Ca2+ channels and other type(s) of Ca2+ channel(s), coupled to glutamate release, are inhibited subsequently to activation of adenosine A1 receptors. |
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Keywords: | Adenosine A1 receptor Striatal synaptosomes Ca2+ channels [Ca2+]i Glutamate release |
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