Progress in Neurobiology Vol. 26, pp. 179 to 209, 1986 0301-0082/86/$0.00 + 0.50 Printed in Great Britain. All rights reserved Copyright © 1986 Pergamon Journals Ltd ADENOSINE RECEPTORS AND CALCIUM: BASIS FOR PROPOSING A THIRD (A3) ADENOSINE RECEPTOR J. A. RIBEIRO and A. M. SEBASTI,~O Laboratory of Pharmacology, Gulbenkian Institute of Science, 2781, Oeiras, Portugal Received 19 September 1985) Contents Abbreviations 1. Introduction 2. Adenosine receptors 2.1. Studies on the effects of adenosine analogues on the adenylate cyclase-cyclic AMP system 2.2. Functional studies 2.3. Binding studies 2.4. Correlation between binding, functional and biochemical effects of adenosine analogues 3. Interactions between adenosine and calcium 3.1. Central nervous system 3.1.1. Pre-synaptic effects of adenosine 3.1.2. Post-synaptic effects of adenosine 3.1.3. Synaptosomes and vesicular preparations 3.1.4. Calcium channel blockers and adenosine 3.2. Neuromuscular junction 3.2.1. Evoked release of transmitter 3.2.2. Spontaneous release of transmitter 3.3. Sympathetic ganglia 3.4. Heart 3.5. Blood vessels 3.5.1. Arteries 3.5.2. Veins 3.6. Smooth muscle 3.6.1. Pre-synaptic effects of adenosine 3.6.2. Smooth muscle contractions 3.7. Adenosine vs calcium--conclusions 4. Potassium 5. Sodium 6. Conclusions Acknowledgements References Abbreviations ACh Acetylcholine ADO Adenosine ATP Adenosine 5'-triphosphate GABA 7-aminobutyric acid 4-AP 4-aminopyridine CADO 2-chloroadenosine cAMP or cyclic AMP Cyclic adenosine-3',5'-monophosphate CHA N6-cyclohexyladenosine NCPCA 5'-N-cyclopropylcarboxamide adenosine DPX 1,3-diethyl-8-phenylxanthine EPPs Endplate potentials NECA 5'-N-etliylcarboxamide adenosine NEM N-ethylmaleimide EPSPs Excitatory post-synaptic potentials FSK Forskolin GTP Guanosine 5'-triphosphate 5-HT 5-Hydroxytryptamine or serotonin LTP Long-term potentiation MEPPs Miniature endplate potentials 179 180 181 182 182 190 191 192 192 192 193 193 194 195 195 197 198 199 200 200 200 200 200 201 201 201 202 203 203 204 J.P.N 26,3--A 179