Abstract
Purpose. A thermodynamic analysis of the binding to rat cortex adenosine A1, receptor of N6-substituted (full agonists) and N6-substituted-deoxyribose (partial agonists) adenosine derivatives was performed. The intrinsic activity of the compounds was evaluated by measurements of the inhibition of forskolin stimulated 3′, 5′-cyclic adenosine mono-phosphate (c-AMP) levels in isolated epididymal rat adipocytes.
Methods. The thermodynamic parameters ΔG° (standard free energy), ΔH °(standard enthalpy), and ΔS° (standard entropy) of the binding equilibrium were determined by means of affinity measurements carried out at different temperatures (0, 10, 20, 25, 30° C). Levels of c-AMP were evaluated performing competitive protein binding assays.
Results. The binding of the ligands increases with temperature enhancement and, as a consequence, is totally entropy driven. Standard entropy values correlate significantly with intrinsic activity ones.
Conclusions. It is proposed the data obtained by these in vitro experiments can be used to investigate the in vivo pharmacodynamic of A1, full and partial agonists.
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Dalpiaz, A., Scatturin, A., Pavan, B. et al. Thermodynamic In Vitro Studies as a Method to Investigate the Pharmacodynamic Behavior of Adenosine A1 Receptor Ligands. Pharm Res 16, 1054–1058 (1999). https://doi.org/10.1023/A:1018987816891
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DOI: https://doi.org/10.1023/A:1018987816891