Sex differences in the systemic response to adrenoreceptor antagonists during sympathetic activation

Background Sex differences in sensitivity to adrenergic agonists have been described in forearm plethysmography studies. The attenuation in noradrenaline-mediated vasoconstriction is because of enhanced β ₂-adrenergic stimulation in women. The systemic relevance of these observations is unknown. The aim of this study was to determine sex inequalities in the systemic haemodynamic response to sympathetic activation by isometric forearm contraction in the presence of adrenoreceptor blockade. Materials and methods Isometric forearm contraction was performed in the presence of isotonic saline, esmolol and phentolamine, respectively, in six men and six premenopausal women. Results Isometric forearm contraction increased heart rate by 9·5%±4·8 CI _95%, P=0·00001 in both sexes. Mean arterial pressure was also increased in both sexes 13·9%±3·2 CI _95%, P=0·002. Esmolol attenuated the rise in mean arterial pressure in men (5·9%±3·6 CI _95%, P=0·6) but not in women (14·3%±3·2 CI _95%, P=0·007). Conclusions This study supports previous findings of sex differences in adrenergic responsiveness and suggests that its consequences are systemically relevant.