Pulmonary arterial hypertension induced in rats decreased intrinsic heart rate and caused significant remodeling of ion channel, Ca2+-handling, and fibrosis genes in the sinus node.
Does pulmonary arterial hypertension cause sinus node remodeling and dysfunction in a rat model?
In a rat model of pulmonary arterial hypertension, sinus node dysfunction is driven by significant molecular remodeling, including the downregulation of ion channels and calcium-handling genes and the upregulation of fibrotic pathways.
Patients with pulmonary arterial hypertension (PAH) have a high burden of arrhythmias, including arrhythmias arising from sinus node dysfunction, and the aim of this study was to investigate the effects of PAH on the sinus node. In the rat, PAH was induced by an injection of monocrotaline. Three weeks after injection, there was a decrease of the intrinsic heart rate (heart rate in the absence of autonomic tone) as well as the normal heart rate, evidence of sinus node dysfunction. In the sinus node of PAH rats, there was a significant downregulation of many ion channels and Ca 2+ -handling genes that could explain the dysfunction: HCN1 and HCN4 (responsible for pacemaker current, I f ), Cav1.2, Cav1.3 and Cav3.1 (responsible for L- and T-type Ca 2+ currents, I Ca,L and I Ca,T ), NCX1 (responsible for Na + –Ca 2+ exchanger) and SERCA2 and RYR2 (Ca 2+ -handling molecules). In the sinus node of PAH rats, there was also a significant upregulation of many fibrosis genes that could also help explain the dysfunction: vimentin, collagen type 1, elastin, fibronectin and transforming growth factor β1. In summary, in PAH, there is a remodelling of ion channel, Ca 2+ -handling and fibrosis genes in the sinus node that is likely to be responsible for the sinus node dysfunction. This article is part of the theme issue ‘The heartbeat: its molecular basis and physiological mechanisms’.
Logantha et al. (Mon,) conducted a other in Pulmonary arterial hypertension. Monocrotaline injection was evaluated on Heart rate and gene expression in the sinus node. Pulmonary arterial hypertension induced in rats decreased intrinsic heart rate and caused significant remodeling of ion channel, Ca2+-handling, and fibrosis genes in the sinus node.