The Validity of Heart Rate Variability Obtained from Electrocardiography and Blood Pressure in Rats Subjected to Isoproterenol-Induced Heart Ischemia

Heart rate variability (HRV) is calculated by electrocardiography (ECG-HRV) or blood pressure (BP-HRV). The purpose of this study was to determine the validity of the above methods in rats with normal and ischemic hearts during the baroreflex maneuver. The study was conducted at Shiraz University of Medical Sciences, Shiraz, Iran, in 2021. Sprague-Dawley rats were divided into a sham group and an isoproterenol-mediated cardiac ischemia (ISO) group. Saline and isoproterenol (150 mg/kg) injected subcutaneously for 2 consecutive days in the sham and ISO groups, respectively. Then, the animals were anesthetized with an intraperitoneal injection of sodium thiopental (60 mg/kg), and the femoral artery and vein were cannulated. Baroreflex was activated using an intravenous injection of phenylephrine (10 μg/100 μL saline). ECG, BP, and heart rate (HR) were recorded, and the time domain of HRV and baroreflex gain were calculated. Baroreflex gain in the ISO group (male, weight=275.8±2.8 g, n=8) was lower than that in the sham group (male, weight=258±2.3 g, n=8) (P