Premium
Cardiac‐specific Overexpression of the α 1A ‐Adrenergic Receptor in Rats: a Model of Enhanced Cardiac Contractility and Autonomically Decreased Heart Rate
Author(s) -
Zhao Xin,
Ho David,
Gao Shumin,
Vatner Dorothy E.,
Graham Robert,
Vatner Stephen F.
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1099.7
Subject(s) - contractility , propranolol , medicine , heart rate , atropine , cardiac function curve , ejection fraction , hemodynamics , endocrinology , cardiac output , blood pressure , muscarinic acetylcholine receptor , cardiology , receptor , heart failure
We examined cardiac function in a novel TG rat model of cardiac specific overexpression of α 1A ‐adrenergic receptors (α 1A ‐ARs). Left ventricular (LV) function was studied in anesthetized TG rats and wild type littermates (NTLs), and heart rate (HR) regulation by telemetry in conscious rats. Cardiac hemodynamics, determined using micromanometry (LV pressure and dP/dt) and echocardiography (ejection fraction, EF), revealed enhanced contractility in TG rats (n=6) vs NTLs (n=7) (+dP/dt: 9752± 159 vs 8067±306mmHg/s, p<0.01; EF: 87±1.2% vs 74±0.7%, p<0.01, respectively), where as LV systolic pressure was not different (122±5 vs 124±6 mmHg, respectively). HR, however, was significantly lower in TG rats vs NTLs (293±5 vs 327±10 bpm, p<0.05), due both to decreased sympathetic drive (diminished HR fall to β‐AR blockade with propranolol, 5 mg/kg: −3±1 vs −11±2 bpm, p<0.05, respectively) and enhanced parasympathetic tone (increased HR rise to muscarinic receptor blockade with atropine, 4 mg/kg: +35±3 vs +23±2 bpm, p<0.05, respectively). Thus, cardiac α 1A ‐ARs overexpression in the rat results in a novel model of enhanced LV contractility and autonomically decreased heart rate.