Spatial variability of vasodilatation in human forearm skin

Area of Science:

• Dermatology
• Physiology
• Pharmacology

Background:

• Topical methyl nicotinate induces skin vasodilatation.
• Variability in vasoconstrictor assays, such as those for corticosteroids, is often observed.
• Understanding regional skin response variations is crucial for accurate physiological and pharmacological assessments.

Purpose of the Study:

• To investigate the regional differences in methyl nicotinate-induced vasodilatation on human ventral forearm skin.
• To determine if forearm laterality (left vs. right) or site (medial vs. lateral) affects the vasodilatation response.
• To compare vasodilatation magnitude at proximal versus distal forearm locations.

Main Methods:

• Photoplethysmography was used to measure vasodilatation.
• Methyl nicotinate was applied topically to various forearm sites in eight healthy subjects.
• Key response parameters recorded included time-to-peak, peak magnitude, area under the curve, and decay time.

Main Results:

• No significant differences in vasodilatation were found between the left and right forearms.
• No significant differences were observed between medial and lateral forearm sites.
• Proximal forearm sites demonstrated significantly higher peak response magnitude and area under the response-time curve compared to distal sites (P < 0.01 and P < 0.05, respectively).

Conclusions:

• Regional variations in forearm skin vasodilatation exist, with proximal sites showing a more pronounced response.
• These findings may help explain variability encountered in vasoconstrictor assays, particularly for corticosteroids.
• The study highlights the importance of considering anatomical location in skin-based physiological measurements.