%0 Journal Article %1 Klotz2007 %A Klotz, K. N. %A Falgner, N. %A Kachler, S. %A Lambertucci, C. %A Vittori, S. %A Volpini, R. %A Cristalli, G. %D 2007 %J Eur J Pharmacol %K & A3/*agonists/metabolism Adenosine Adenosine/*analogs Animals Assay CHO Cricetinae Cricetulus Humans Kinetics Ligands Radioligand Sensitivity Specificity Tritium and derivatives/pharmacology Receptor Cell %N 1-3 %P 14-8 %T 3HHEMADO--a novel tritiated agonist selective for the human adenosine A3 receptor %U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17126322 %V 556 %X Adenosine A(3) receptors are promising drug targets for a number of conditions like inflammatory diseases including asthma, ischemic injury or certain types of cancer. Consequently, intense efforts are dedicated to the development of selective A(3) agonists and antagonists. The only tritiated agonist that is available for radioligand binding is the nonselective (3)H5'-N-ethylcarboxamidoadenosine ((3)HNECA). Based on a recently characterized series of 2-substituted adenosine receptor agonists we developed a tritiated selective A(3) radioligand with high affinity. From this series 2-hexyn-1-yl-N(6)-methyladenosine (HEMADO) with a K(i)-value of 1.1 nM at the human A(3) subtype was chosen. HEMADO is 300-fold selective versus the A(1) subtype, and 1100-fold and more than 25,000-fold selective compared to the adenosine A(2A) and A(2B) receptors, respectively. The tritiated derivative (3)HHEMADO exhibited the same affinity as the unlabeled precursor. In concentrations up to 10 nM no specific binding to adenosine A(1), A(2A) or A(2B) receptors was observed confirming the high selectivity for adenosine A(3) receptors. Characterization of (3)HHEMADO in radioligand binding studies revealed reversible binding to the human adenosine A(3) subtype. In saturation binding studies for the A(3) subtype a K(D)-value of 1.1 nM was determined. Nonspecific binding at a radioligand concentration of 1 nM amounted to 1-2% of total binding. Competition binding with a panel of adenosine receptor ligands clearly confirmed the correct A(3) pharmacology of the binding site labeled by (3)HHEMADO. With (3)HHEMADO we present a tritiated agonist with high affinity and A(3)-selectivity and very low nonspecific binding. (3)HHEMADO is a useful tool for specific screening for A(3) receptor agonists and antagonists in improved radioligand binding assays with the human subtype.

@article{Klotz2007, abstract = {Adenosine A(3) receptors are promising drug targets for a number of conditions like inflammatory diseases including asthma, ischemic injury or certain types of cancer. Consequently, intense efforts are dedicated to the development of selective A(3) agonists and antagonists. The only tritiated agonist that is available for radioligand binding is the nonselective [(3)H]5'-N-ethylcarboxamidoadenosine ([(3)H]NECA). Based on a recently characterized series of 2-substituted adenosine receptor agonists we developed a tritiated selective A(3) radioligand with high affinity. From this series 2-hexyn-1-yl-N(6)-methyladenosine (HEMADO) with a K(i)-value of 1.1 nM at the human A(3) subtype was chosen. HEMADO is 300-fold selective versus the A(1) subtype, and 1100-fold and more than 25,000-fold selective compared to the adenosine A(2A) and A(2B) receptors, respectively. The tritiated derivative [(3)H]HEMADO exhibited the same affinity as the unlabeled precursor. In concentrations up to 10 nM no specific binding to adenosine A(1), A(2A) or A(2B) receptors was observed confirming the high selectivity for adenosine A(3) receptors. Characterization of [(3)H]HEMADO in radioligand binding studies revealed reversible binding to the human adenosine A(3) subtype. In saturation binding studies for the A(3) subtype a K(D)-value of 1.1 nM was determined. Nonspecific binding at a radioligand concentration of 1 nM amounted to 1-2% of total binding. Competition binding with a panel of adenosine receptor ligands clearly confirmed the correct A(3) pharmacology of the binding site labeled by [(3)H]HEMADO. With [(3)H]HEMADO we present a tritiated agonist with high affinity and A(3)-selectivity and very low nonspecific binding. [(3)H]HEMADO is a useful tool for specific screening for A(3) receptor agonists and antagonists in improved radioligand binding assays with the human subtype.}, added-at = {2010-12-14T18:12:02.000+0100}, author = {Klotz, K. N. and Falgner, N. and Kachler, S. and Lambertucci, C. and Vittori, S. and Volpini, R. and Cristalli, G.}, biburl = {https://www.bibsonomy.org/bibtex/2e16a8f48b40d026862dec63358531fc9/pharmawuerz}, endnotereftype = {Journal Article}, interhash = {fb206993d1fb58bbf17fb83d7972fbaa}, intrahash = {e16a8f48b40d026862dec63358531fc9}, issn = {0014-2999 (Print) 0014-2999 (Linking)}, journal = {Eur J Pharmacol}, keywords = {& A3/*agonists/metabolism Adenosine Adenosine/*analogs Animals Assay CHO Cricetinae Cricetulus Humans Kinetics Ligands Radioligand Sensitivity Specificity Tritium and derivatives/pharmacology Receptor Cell}, month = {Feb 5}, note = {Klotz, Karl-Norbert Falgner, Nico Kachler, Sonja Lambertucci, Catia Vittori, Sauro Volpini, Rosaria Cristalli, Gloria Research Support, Non-U.S. Gov't Netherlands European journal of pharmacology Eur J Pharmacol. 2007 Feb 5;556(1-3):14-8. Epub 2006 Oct 27.}, number = {1-3}, pages = {14-8}, shorttitle = {[3H]HEMADO--a novel tritiated agonist selective for the human adenosine A3 receptor}, timestamp = {2010-12-14T18:20:39.000+0100}, title = {[3H]HEMADO--a novel tritiated agonist selective for the human adenosine A3 receptor}, url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17126322}, volume = 556, year = 2007 }