Abstract
Binding characteristics of human cortical membrane fractions were evaluated to test the hypothesis that there are A1 and A2 adenosine binding sites. Binding of chloroadenosine was time dependent, reversible and concentration dependent. The Kd for chloroadenosine was 280 nM with a Bmax of 1.6 pmoles/mg protein. The apparent Kd was estimated to be 0.74 μM for 5'-N-ethylcarbox-amideadenosine, 1 μM cyclohexyladenosine, 13 μM N6-(L-2-phenylisopropyl)adenosine, 84 μM isobutylmethylxanthine and 105 μM theophylline. Hill slope factors ranged from 0.3 to 0.6. The kob was 0.080 min−1, the K1 7.5 × 104 min−1M−1, and the k2 .074 min−1. The Kd calculated from the rate constants was 990 nM. Cyclohexyladenosine binding was concentration dependent and the Kd was 5 nM with a Bmax of 0.35 pmoles/mg protein. Cyclohexyladenosine binding was displaced by N6-(L-2-phenylisopropyl)adenosine (Kd 4 nM), 2-chloroadenosine (Kd 10 nM), 5'-N-ethylcarboxamideadenosine (Kd 6 nM), isobutylmethylxanthine (4 μM) and theophylline (8 μM). Hill slope factors ranged from 0.5 to 0.8.
Our data support the existence of two adenosine binding sites in human cortex compatable with low affinity (A2) and high affinity (A1) adenosine receptors.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
John, D., Fox, I. CHARACTERISTICS OF HIGH AFFINITY AND LOW AFFINITY ADENOSINE BINDING SITES IN HUMAN CEREBRAL CORTEX: 96. Pediatr Res 19, 759 (1985). https://doi.org/10.1203/00006450-198507000-00116
Issue Date:
DOI: https://doi.org/10.1203/00006450-198507000-00116