Cardiac overexpression of the human 5-HT4 receptor in mice

Am J Physiol Heart Circ Physiol. 2010 Sep;299(3):H788-98. doi: 10.1152/ajpheart.00691.2009. Epub 2010 Jul 16.


Serotonin (5-HT) exerts pleiotropic effects in the human cardiovascular system. Some of the effects are thought to be mediated via 5-HT(4) receptors, which are expressed in the human atrium and in ventricular tissue. However, a true animal model to study these receptors in more detail has been hitherto lacking. Therefore, we generated, for the first time, a transgenic (TG) mouse with cardiac myocyte-specific expression of the human 5-HT(4) receptor. RT-PCR and immunohistochemistry revealed expression of the receptor at the mRNA and protein levels. Stimulation of isolated cardiac preparations by isoproterenol increased phospholamban phosphorylation at Ser(16) and Thr(17) sites. 5-HT increased phosphorylation only in TG mice but not in wild-type (WT) mice. Furthermore, 5-HT increased contractility in isolated perfused hearts from TG mice but not WT mice. These effects of 5-HT could be blocked by the 5-HT(4) receptor-selective antagonist GR-125487. An intravenous infusion of 5-HT increased left ventricular contractility in TG mice but not in WT mice. Similarly, the increase in contractility by 5-HT in isolated cardiomyocytes from TG mice was accompanied by and probably mediated through an increase in L-type Ca(2+) channel current and in Ca(2+) transients. In intact animals, echocardiography revealed an inotropic and chronotropic effect of subcutaneously injected 5-HT in TG mice but not in WT mice. In isolated hearts from TG mice, spontaneous polymorphic atrial arrhythmias were noted. These findings demonstrate the functional expression of 5-HT(4) receptors in the heart of TG mice, and a potential proarrhythmic effect in the atrium. Therefore, 5-HT(4) receptor-expressing mice might be a useful model to mimic the human heart, where 5-HT(4) receptors are present and functional in the atrium and ventricle of the healthy and failing heart, and to investigate the influence of 5-HT in the development of cardiac arrhythmias and heart failure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Blotting, Western
  • Echocardiography
  • Heart / physiology*
  • Immunohistochemistry
  • Mice
  • Mice, Transgenic
  • Myocardial Contraction / physiology*
  • Myocardium / metabolism*
  • Myocytes, Cardiac / metabolism*
  • Phosphorylation
  • Receptors, Serotonin, 5-HT4 / genetics
  • Receptors, Serotonin, 5-HT4 / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / physiology


  • Receptors, Serotonin, 5-HT4