Abstract 4368: Differential Left versus Right Atrial Transcriptional Response to Angiotensin Stimulation
Introduction: Angiotensin stimulation is associated with atrial arrhythmias. Atrial fibrillation is commonly initiated in the left atrium. Cardiac over-expression of members of the angiotensin receptor signaling pathway correlates with atrial dilatation. Similarly cardiac over-expression of the inhibitory basic leucine zipper (bZIP) transcription factors JDP2 and ATF3 result in atrial dilatation. We have recently found a signaling pathway in which Angiotensin and Isoproterenol induce ATF3 experssion in the atria.
Hypothesis: ATF3 expression may differ in left versus right atria.
Methods and Results: mice were IP injected with Angiotensin, Isoproterenol or Saline. ATF3 expression in the left and right atria and in ventricles was analyzed using western blots and by immuno- histochemisty staining of paraffin embedded sections. Whereas Isoproterenol induced ATF3 expression in both atria and in ventricular tissue. Angiotensin induced ATF3 expression in the left atrium and in the ventricls but not in the right atrium (fig⇓). Analysis for other bZIP transcription factors revealed a responce to angiotensin in both atria.
Conclusions and Implication: Angiotensin but not isoproterenol induces ATF3 expression differentially in the left but not right atria. To the best of our knowledge this is the first description of left atrial specific angiotensin mediated expression. This finding may be important in understanding atrial pathophysiological response to hemodynamic challenge and pathologies such as dilatation and generation of arrhythmia.