Adenosine A sub(1) receptors inhibit Ca super(2+) channels coupled to the release of ACh, but not of GABA, in cultured retina cells

• Published in: Brain research 2000-01, Vol.852 (1), p.10-15
• Main Authors: Santos, P F, Caramelo, O L, Carvalho, AP, Duarte, C B
• Format: Article
• Language: English
• ISSN: 0006-8993

We investigated the effect of adenosine A sub(1) receptors on the release of acetylcholine (ACh) and GABA, and on the intracellular calcium concentration ([Ca super(2+)] sub(i)) response in cultured chick amacrine-like neurons, stimulated by KCl depolarization. The KCl-induced release of [ super(3) H ]ACh, but not the release of [ super(14)C]GABA, was potentiated when adenosine A sub(1) receptor activation was prevented by perfusing the cells with adenosine deaminase (ADA) or with 1,3-dipropyl-8-cycloentylxanthine (DPCPX). The changes in the [Ca super(2+)] sub(i) induced by KCl depolarization, measured in neurite segments of single cultured cells, were also modulated by endogenous adenosine, acting on adenosine A sub(1) receptors. Our results show that adenosine A sub(1) receptors inhibit Ca super(2+) entry coupled to ACh release, but not to the release of GABA, suggesting that the synaptic vesicles containing each neurotransmitter are located in different zones of the neurites, containing different VSCC and/or different densities of adenosine A sub(1) receptors.