Trandolapril Attenuates Pro-Arrhythmic Downregulation of Cx43 and Cx40 in Atria of Volume Overloaded Hypertensive and Normotensive Rats

Pressure overload in non-treated or resistant hypertension (HTN) increases the risk of heart failure (HF) as well as the occurrence of fatal ventricular arrhythmias and stroke-provoking atrial fibrillation (AF), while perturbed connexin-43 (Cx43) and Cx40 might be involved. In addition, kidney dysfunction may facilitate hemodynamic volume overload and congestive HF. We investigated the impact of volume overload on Cx43 and Cx40 in right and left heart atria of hypertensive pressure overloaded Ren-2 transgenic (TGR) strain and normotensive Hannover Sprague Dawley (HSD) rats, as well as the efficacy of renin-angiotensin blockade with trandolapril and losartan. Key novel findings revealed lower levels of Cx43 and Cx40 proteins in left as well as right heart atria in pressure overloaded hypertensive rats compared to normotensive rats. There was a significant decrease in Cx43 and Cx40 proteins due to volume overload in both atria of normotensive as well as hypertensive rats. Treatment with trandolapril increased Cx43 and Cx40 levels in right and left heart atria of normotensive as well as hypertensive volume overloaded rats. While losartan increased Cx43 and did not affect Cx40 in left and right heart atria of volume overloaded rats. Findings of this study point out that right heart atria of normotensive as well as hypertensive rats are more susceptible to volume overload comparing to the left heart atria. Trandolapril attenuated pro-arrhythmic downregulation of Cx43 and Cx40 in atria of volume overloaded normotensive as well as hypertensive rats. This fact as well as examining AF inducibility requires further investigation.