Comparison of the densities of 5-HT4 receptors, ?1- and ?2-adrenoceptors in human atrium: functional implications
- 1 April 1996
- journal article
- Published by Springer Nature in Naunyn-Schmiedebergs Archiv für experimentelle Pathologie und Pharmakologie
- Vol. 353 (5) , 592-595
- https://doi.org/10.1007/bf00169181
Abstract
We measured in human atrium the density of 5-HT4 receptors, labelled with [125I]-SB 207710 (1-butyl-4-piperidinyl) methyl 8-amino-7-iodo-1, (4-benzodioxan-5-carboxylate), and compared it with the density of β1- and β2-adrenoceptors, labelled with (−)-[125I]-cyanopindolol. [125I]-SB 207710 (5–1200 pmol/l) labelled a small population of saturable binding sites (B max ≈ 4 fmol/mg protein) with a pKD of 9.7 and with 5-HT4 receptor characteristics, as assessed with competing ligands. The density of atrial binding sites with 5-HT4 receptor characteristics was 10 and 5 times lower, respectively, than the density of β1- and β2-adrenoceptors. We suggest that the small 5-HT4 receptor population may in part explain why the positive inotropic effects of 5-HT are smaller than those of catecholamines mediated through β1- and β2-adrenoceptors.Keywords
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