| Autor: |
Cai, John J., Morgan, Donald A., Haynes, William G., Martins, James B., Lee, Hon-Chi |
| Předmět: |
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| Zdroj: |
American Journal of Physiology: Heart & Circulatory Physiology; Dec2002, Vol. 283 Issue 6, pH2606, 6p, 1 Diagram, 1 Chart, 4 Graphs |
| Abstrakt: |
We previously reported that α[sub 2]-adrenergic receptor (α[sub 2]-AR) stimulation in Purkinje fibers in vitro prolongs action potential duration and suppresses β-adrenergic-induced delayed afterdepolarizations and sustained triggered activities. We examined the effects of α[sub 2]-AR stimulation on reperfusion-induced ventricular arrhythmias [ventricular tachycardia/ventricular fibrillation (VT/VF)] in vivo. Arterial blood pressure, heart rate, surface electrocardiogram, and renal sympathetic nerve activities were recorded simultaneously in Sprague-Dawley rats. The incidence of VT/VF was 87.5% for controls, 50% for the β-blocker group, 72% for the α[sub 1]-blocker group, and 12.5% for the α[sub 1] + β-blockers group (unopposed α[sub 2]-adrenergic activation). Direct α[sub 2]-AR stimulation with UK-14304 also prevented VT/VF. These effects were reversed by the α[sub 2]-adrenergic antagonist yohimbine. Increases in renal sympathetic nerve activity were associated with left anterior descending coronary artery ligation and reperfusion (33 ± 1.5 and 62 ± 1.7% over baseline, respectively) in controls. Similar patterns were observed among all experimental groups irrespective of the incidence of VT/VF on reperfusion. We conclude that α[sub 2]-AR stimulation has a potent antiarrhythmic effect on ischemia-reperfusioninduced VT/VF in vivo and that this effect is not centrally mediated. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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