Characteristics of high-affinity [3H]adenosine binding to rat brain synaptosomes and turkey erythrocyte membranes |
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Authors: | Michael Newman Alexander Levitzki |
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Institution: | Hebrew University of Jerusalem, Department of Biological Chemistry, Institute of Life Sciences, Jerusalem 91904 Israel |
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Abstract: | High affinity binding sites for 3H]adenosine in rat brain and in turkey erythrocytes can be identified by binding experiments. Displacement experiments using a number of adenosine analogs indicate that these high affinity sites do not represent the R-type adenosine receptors which mediate activation of adenylate cyclase, although the binding is theophylline sensitive. Similarly, the binding of 3H]adenosine is not to the P-site, which mediates inhibition of adenylate cyclase, since the high affinity binding persists in the presence of 2′,5′-dideoxyadenosine. Furthermore, these results remain qualitatively similar also in the presence of dipyridamole which blocks adenosine transport sites. We conclude that theophylline sensitivity does not indicate that 3H]adenosine binding sites correspond to adenosine receptors coupled to adenylate cyclase. |
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Keywords: | Adenosine receptor Binding site (Rat brain Turkey erythrocyte) EHNA erythro-9-(2-hydroxy-3-nonyl) adenine IBMX 3-isobutyl-1-methylxanthine |
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