Abstract 14772: Cardiac Vagal Control in Knock-in Mouse model of Dilated Cardiomyopathy

BackgroundIt has been reported that cardiac vagal nerve activity is reduced in heart failure, but cardiac vagal nerve activity in heart failure has only been evaluated by indirect methods in mice.ObjectiveTo evaluate cardiac vagal nerve activity and identify the abnormality of cardiac vagal control in heart failure using a knock-in mouse model of dilated cardiomyopathy (DCM) with ΔK210 mutation in the cardiac troponin T gene.MethodsMicrodialysis technique was applied to the left ventricular myocardium of anesthetized mice and myocardial interstitial acetylcholine (ACh) levels were measured by HPLC as an index of ACh release from cardiac vagal nerve endings. The effects of electrical stimulation of left cervical vagal nerves at 5 and 10 Hz (peripheral vagal control) and alpha-2 adrenergic stimulation by intravenous medetomidine at 0.1 mg/kg (central vagal control) were examined in wild-type (WT) mice (n=7) and DCM mice (n=7).ResultsAt baseline, heart rate was lower (390 ± 8 vs. 415 ± 4 bpm, P