Effects of pioglitazone on electrocardiogram parameters and heart rate variability in isoproterenol- induced cardiac ischemia in rat

Abstract

Abstract Background In this study, we aimed to determine whether short-term treatment with PPAR-γ agonist pioglitazone could influence electrocardiogram (ECG) parameters and heart rate variability (HRV) in isoproterenol-induced cardiac ischemia at rest and after phenylephrine injection. Methods Male Sprague-Dawley rats were divided into Sham, pioglitazone (PIO, 3 mg/kg, i.p.), isoproterenol-induced cardiac ischemia (ISO, 150 mg/kg, subcutaneously at 24-hour intervals on days 4 and 5), and PIO + ISO groups. Saline (in the Sham and ISO groups) or pioglitazone (in the PIO and PIO + ISO groups) were administered for 5 days. On day 6, tracheostomy and cannulation of the femoral artery and vein were performed under deep anesthesia. Then, blood pressure (BP) and ECG were recorded and HRV analysed. Results Baroreflex induced by intravenous injection of phenylephrine (10 µg/0.1 ml) increased BP and decreased heart rate (HR) in all groups. HR, QT interval, and QTc in the ISO group were more than in the Sham group at baseline and in baroreflex. Pioglitazone decreased the mentioned parameters in the PIO + ISO group. HRV analysis showed reductions in parasympathetic components of HRV in the ISO group, whereas pioglitazone corrected it in the PIO + ISO group. Cardiac markers, malondialdehyde, white blood cells, and heart/body weight ratio were more in the ISO group than those in the Sham group. All mentioned parameters were lower in the PIO + ISO group than those in the ISO group. Conclusion We indicated pioglitazone improves the electrical conduction of the heart and HRV in cardiac ischemia through modulating the inflammatory reactions.