Within-limb variation in skin pigmentation does not influence cutaneous vasodilation.

Area of Science:

• Physiology
• Dermatology
• Vascular Biology

Background:

• Nitric oxide (NO) is crucial for cutaneous vasodilation.
• Ultraviolet radiation (UVR) exposure and higher constitutive skin melanin reduce NO-dependent vasodilation.
• The effect of seasonal UVR-induced skin melanin variation on NO-mediated vasodilation is unknown.

Purpose of the Study:

• To investigate how within-limb variations in skin melanin, due to seasonal UVR exposure, affect NO-dependent cutaneous vasodilation.

Main Methods:

• Seven adults with light skin pigmentation were studied.
• Melanin-index was measured on the inner-upper arm, ventral forearm, and dorsal forearm.
• Local heating induced vasodilation, followed by NO synthase inhibition (l-NAME) to quantify NO's contribution, measured by Laser-Doppler flowmetry.

Main Results:

• The dorsal forearm had a higher melanin-index than the ventral forearm and upper arm.
• Cutaneous vasodilation responses to local heating did not differ among the sites.
• Neither the magnitude of vasodilation nor the NO-mediated component varied significantly across the different skin pigmentation sites.

Conclusions:

• Within-limb variations in skin pigmentation from seasonal UVR exposure do not alter NO-dependent cutaneous vasodilation in lightly pigmented skin.
• Seasonal UVR exposure does not impact the NO-mediated function of the cutaneous microvasculature.