Are there age and racial differences to methyl nicotinate-induced vasodilatation in human skin?

Preliminary experiments have been performed to determine whether there are age and racial differences in the response of human skin to the topically applied vasodilator methyl nicotinate. With the use of a constant stimulus (a 15-second exposure to a 100 mM aqueous solution of drug), the subsequent time-course of the vasodilatation response was followed noninvasively and objectively with the optical technics of laser Doppler velocimetry (LDV) and photoplethysmography (PPG). Three groups of subjects were considered: young white subjects (20 to 30 years of age), elderly white subjects (63 to 80 years old), and young black subjects (20 to 30 years old). Analysis of the results shows that the time to peak response, the area under the response-time curve, and the time for the response to decay to 75% of its maximum value are statistically indistinguishable for all three groups at the p = 0.05 level of significance. Only the magnitude of the peak response revealed some significant differences between the cohorts (young greater than black, determined by PPG; young greater than old, determined by LDV). The data suggest, therefore, a remarkable similarity in response across a wide range of skin types. The origin of this consistency may, however, be complex and is not revealed by these experiments.