Abstract
Aortic regurgitation (AR) produces a volume overload to the heart. Acute AR determines poor prognostic, and its main cause is infective endocarditis. The role of autonomic participation on this situation is still missing. We studied hemodynamic parameters, autonomic modulation, heart rate (HR) variability and baroreflex sensibility (BRS) in acute AR rats.Male Wistar rats (250‐280g) were undergone to sham or AR surgery. Following one week the rats received a catheter into the femoral artery (direct measurements of arterial pressure, AP), and another into the jugular vein (drug administration). Intrinsic HR (IHR) was evaluated after simultaneous blockade with atenolol (6 mg/kg) and atropine (3 mg/kg). The sympathetic tonus (ST) and vagal tonus (VT) were obtained from IHR minus the maximum HR after atropine and the lowest HR after atenolol, respectively. Overall variability of HR in the time domain and BRS were calculated from basal recordings. Diastolic pressure was lower in AR rats(70 ± 6 vs sham 99 ± 5 mmHg). There were no changes for IHR, ST, VT or HR variability. Acute AR impaired BRS (1,10 ± 0,11 vs sham 1,61 ± 0,14 ms/mmHg). The results show that acute AR does not altered autonomic modulation to the heart, although it produces a decrease in the BRS, this import mechanism is dismished in onset sustained volume overload to the heart. Financial support: FAPESP 2013/00742‐7
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