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The ability of denbufylline to inhibit cyclic nucleotide phosphodiesterase and its affinity for adenosine receptors and the adenosine re‐uptake site
Author(s) -
Nicholson C.D.,
Jackman S.A.,
Wilke R.
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb12029.x
Subject(s) - ibmx , adenosine , phosphodiesterase , theophylline , adenosine receptor , cyclic nucleotide phosphodiesterase , chemistry , receptor , endocrinology , phosphodiesterase inhibitor , medicine , biochemistry , biology , forskolin , enzyme , agonist
1 Denbufylline has been examined for its ability to inhibit cyclic nucleotide phosphodiesterase isoenzymes from rat cardiac ventricle and cerebrum, as well as for its affinity for adenosine A 1 and A 2 receptors and the re‐uptake site. For comparison, SK&F 94120, theophylline and 3‐isobutyl‐1‐methyl‐xanthine (IBMX) were examined as phosphodiesterase inhibitors whilst N 6 ‐cyclohexyladenosine, R(−)‐N 6 ‐(2‐phenylisopropyl)‐adenosine, 5′‐N‐ethylcarboxamido‐adenosine, 2‐nitrobenzylthioinosine, theophylline and IBMX were examined for their affinity for adenosine binding sites. 2 This investigation confirmed the presence of four phosphodiesterase activities in rat cardiac ventricle; in rat cerebrum only three were present. 3 Denbufylline selectively inhibited one form of Ca 2+ ‐independent, low K m cyclic AMP phosphodiesterase. The form inhibited was one of two present in cardiac ventricle and the sole one in cerebrum. This form was not inhibited by cyclic GMP. The inotropic agent SK&F 94120 selectively inhibited the form of cyclic AMP phosphodiesterase which was inhibited by cyclic GMP present in cardiac ventricle. Theophylline and IBMX were relatively non‐selective phosphodiesterase inhibitors. 4 Denbufylline was a less potent inhibitor of ligand binding to adenosine receptors than of cyclic AMP phosphodiesterase. This contrasted with theophylline, which had a higher affinity for adenosine receptors, and IBMX which showed no marked selectivity. Denbufylline, theophylline and IBMX all had a low affinity for the adenosine re‐uptake site. 5 Denbufylline is being developed as an agent for the therapy of multi‐infarct dementia. The selective inhibition of a particular low K m cyclic AMP phosphodiesterase may account for the activity of this compound.