Influence of gender on vascular reactivity in the rat

Tail artery ring segments and the isolated perfused mesenteric vascular bed from male, female metestrus and female proestrus Fisher 344 rats were used to study the influence of estrous cycle or gender on vascular reactivity. Vasodilator effects of nicotine on mesenteric vasculature and tail artery ring segments were not significantly different among the three groups. In the presence of guanethidine and methoxamine, transmural nerve stimulation of capsaicin-sensitive sensory nerves caused essentially the same level of frequency-dependent vasodilation in isolated perfused mesenteric vasculature in all three groups. Vasodilator responses to acetylcholine were not different with estrous cycle or gender. In tail artery ring segments, stage of estrous cycle or gender did not affect sensitivity to norepinephrine. Sensitivity to adrenergic nerve stimulation was significantly greater in male compared to female rats, but was not affected by estrous cycle stage. These data suggest that in the perfused mesentery vasodilator responsiveness to capsaicin-sensitive sensory nerve stimulation caused by either nicotine or transmural nerve stimulation is unaffected by gender or the estrous cycle, and endothelial function is also not influenced. Sensitivity to norepinephrine is also not affected, whereas sensitivity to adrenergic nerve stimulation is greater in males compared to females. Thus estrous cycle did not affect vascular responsiveness, but there were gender-related differences.