Comparing cutaneous NO-dependent vasodilation between young males and females
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Background
Despite the common use of local heating and intradermal microdialysis perfusion of acetylcholine (ACh) to probe cutaneous endothelium and nitric oxide (NO)-dependent dilation, sex differences in microvascular responsiveness to these stimuli in healthy young adults remain incompletely understood.
Methods
Cutaneous vasodilation was assessed in response to local heating to 39°C and 42°C and graded perfusion of ACh (10 -10 to 10 -1 mol/L) alone or concurrently with 15 mM N G -nitro-L-arginine methyl ester (L-NAME; NO synthase inhibitor) using laser-Doppler flowmetry coupled with intradermal microdialysis in 80 young adults (40 females).
Results
Local heating to 42°C elicited greater endothelium- and NO-dependent dilation than heating to 39°C in both groups (p<0.001), but no sex differences were observed at either temperature (p=0.65). ACh-induced endothelium-dependent dilation also was not different between sexes (p=0.08), but the NO-dependent component was greater in females than in males (p=0.01). In young females, menstrual cycle day (range: day 2-33) was not associated with endothelium- or NO-dependent dilation in response to any stimulus (all p≥0.19), regardless of hormonal contraceptive use.
Conclusions
Taken together, these findings suggest that sex differences in microvascular NO bioavailability in healthy young adults depend on the stimulus used to elicit cutaneous vasodilation and, in females, microvascular endothelium- and NO-dependent dilation are not meaningfully influenced by menstrual cycle phase.
