Noradrenaline content and release in male and female rat tail arteries

In tail-artery segments isolated from male and female control and gonadectomized rats, noradrenaline content and noradrenaline released by electrical stimulation were measured by high-pressure liquid chromatography. Noradrenaline content, expressed as a function of tissue wet weight, was higher in tail arteries from female than from male rats, but there were no significant differences between control and orchiectomized males or control and ovariectomized females. Electrical stimulation of vascular segments in the presence of cocaine (10(-5) M) and deoxycorticosterone (10(-5) M) induced release of noradrenaline that was increased in the presence of the alpha(2)-adrenergic antagonist idaxozan (10(-6) M). However, no differences were found in either basal or stimulation-evoked fractional noradrenaline release between male or female, control or gonadectomized animals. These results indicate that control of noradrenaline release at the nerve ending does not appear to be different between genders. There may be differences in adrenergic density, but noradrenaline content does not appear to be modified by circulating gonadal hormones.