Author + information
- John Guersa,b,
- Seonghun Yoona,b,
- Jie Zhanga,b,
- Xin Zhaoa,b,
- Dorothy E. Vatnera,b,
- Robert Grahama,b and
- Stephen F. Vatnera,b
Background: Patients placed on α1A-adrenergic receptor (α1A-AR) blockers tend to be more susceptible to heart failure, whereas α1A-AR agonists may be therapeutic for patients with myocardial ischemia. The goal of this investigation was to examine the extent to which coronary artery occlusion (CAO) affected infarct size, arrhythmias and myocardial blood flow in transgenic (TG) rats with cardiomyocyte-specific α1A-adrenergic receptor overexpression.
Methods: Transgenic rats with cardiomyocyte-specific α1A-adrenergic receptor overexpression underwent permanent CAO. EKGs were recorded for twenty-four hours by telemetry following CAO. Microspheres were used one day following CAO to measure coronary blood flow. Following sacrifice, the area of infarction was measured in the left ventricle by triphenyltetrazolium chloride (TCC) staining.
Results: One day following permanent CAO, transgenic rats with cardiomyocyte-specific α1A-adrenergic receptor overexpression had a lower percentage of left ventricular infarction (22 ± 4%), P<0.05 when compared to WT littermates (35 ± 4%). The percentage of heart beats that were arrhythmic were significantly decreased, p<0.05, following CAO in α1A-adrenergic-TG rats (12 ± 2%) vs. WT (88 ± 2.3%). In addition, 100% of WT rats experienced ventricular tachycardia following CAO, while this only occurred in 25% of the α1A-AR-TG rats. Coronary blood flow, was greater in the area adjacent to the infarct at 1 day following CAO in α1A-adrenergic-TG rats (5.1 ± 0.3 ml/min/kg), P<0.05, when compared with non-transgenic littermates (2.8 ± 0.5 ml/min/kg).
Conclusions: Overexpression of the α1A-adrenergic receptors resulted in even more marked protection against arrhythmias following CAO than the extent of reduction in infarct size, when compared to WT littermates. A potential mechanism for these salutary effects was the increased blood flow to the myocardium in the area at risk adjacent to the infarct.
Poster Hall, Hall C
Saturday, March 18, 2017, 9:45 a.m.-10:30 a.m.
Session Title: Arrhythmias and Clinical EP: Basic 3
Abstract Category: 4. Arrhythmias and Clinical EP: Basic
Presentation Number: 1191-113
- 2017 American College of Cardiology Foundation