ISSN:
1573-4919
Keywords:
α1A-adrenoceptors
;
regional ischaemia
;
reperfusion-induced arrhythmias
;
dual coronary perfusion
;
abanoquil
;
WB4101
;
rat heart
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Abstract Stimulation of α1-adrenoceptors (AR) during ischaemia in the rat heart by exogenous phenylephrine exacerbates reperfusion arrhythmias, an effect apparently mediated by the α1A-AR subtype. We tested whether α1A-AR stimulation byendogenous catecholamines, released during ischaemia, could modulate reperfusion arrhythmias, using as pharmacological tools the selective α1A-AR antagonists abanoquil (UK52046) and WB4101. Isolated rat hearts (n=12/group) were subjected to dual coronary perfusion. After 15 min of aerobic perfusion of both coronary beds, abanoquil or WB4101 was infused selectively into the left coronary bed (LCB) for 5 min. The LCB was then subjected to 10 min of zero-flow ischaemia and 5 min of reperfusion. Effects on PR interval, width of the ventricular complex (QRST90) and reperfusion arrhythmias were assessed. Abanoquil at concentrations of 0.03, 0.1 and 0.3 μM tended to reduce the incidence of reperfusion-induced ventricular fibrillation (VF) in a dose-dependent manner from 75% in controls to 58, 33 and 25%, but this effects did not achieve statistical significance. Similarly, WB4101 at 0.1, 0.3 and 1 μM also tended to reduce VF incidence from 67% in controls to 67, 42% and 33% (NS). The incidence of ventricular tachycardia (VT) was 100% in all groups and ECG parameters were not altered significantly by either drug. These results suggest that, in this denervated isolated heart preparation, α1A-AR stimulation during ischaemia by endogenous catecholamines does not significantly modulate reperfusion arrhythmias.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00944798
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