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Sex influences the susceptibility to reperfusion-induced sustained ventricular tachycardia and -adrenergic receptor blockade in conscious rats

Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan

Submitted 22 May 2007 ; accepted in final form 10 July 2007

Reperfusion after a brief period of cardiac ischemia can lead to potentially lethal arrhythmias. Importantly, there are sex-related differences in cardiac physiology and in the types and severity of cardiac arrhythmias. Therefore, we tested the hypothesis that gonadal hormones influence the susceptibility to reperfusion-induced sustained ventricular tachycardia (VT), as well as the response to -adrenergic receptor blockade. Male and female intact and gonadectomized rats were instrumented, and arterial pressure, temperature, ECG, and cardiac output were recorded. In addition, a snare was placed around the left main coronary artery. Tension was applied to the snare for determination of susceptibility to sustained VT produced by 3 min of occlusion and reperfusion of the left main coronary artery in conscious rats. Reperfusion culminated in sustained VT in 77% (10 of 13 susceptible) of female rats and 56% (9 of 16 susceptible) of male rats (P > 0.05, male vs. female). -Adrenergic receptor blockade prevented sustained VT in females only [1 of 9 susceptible females (11%) vs. 6 of 9 susceptible males (67%), P < 0.05]. Ovariectomy did not significantly reduce the susceptibility to reperfusion arrhythmias [5 of 9 susceptible (56%)]. In sharp contrast, orchidectomy significantly increased the susceptibility to reperfusion arrhythmias [9 of 9 susceptible (100%)]. Finally, -adrenergic receptor blockade prevented sustained VT in ovariectomized females [0 of 4 susceptible (0%)] and orchidectomized males [0 of 7 susceptible (0%)], but the protective effect of -blockade was due to a reduction in heart rate in males only. Thus gonadal hormones influence the susceptibility to reperfusion-induced arrhythmias, as well as the effects and mechanisms of -adrenergic receptor blockade.

cardiovascular risks; arrhythmia; sex differences

This article has been cited by other articles:

				H. L. Lujan and S. E. DiCarlo Sex differences to myocardial ischemia and {beta}-adrenergic receptor blockade in conscious rats Am J Physiol Heart Circ Physiol, April 1, 2008; 294(4): H1523 - H1529. [Abstract] [Full Text] [PDF]