Effect of age on cutaneous vasomotor responses during local skin heating

This study examined the effect of ageing on the low-frequency oscillations (vasomotion) of skin blood flow in response to local heating (LH). Skin blood flow was assessed by laser-Doppler flowmetry on the forearm at rest (33 C-omicron) and in response to LH of the skin to both 42 C-omicron and 44 C-omicron in 14 young (24 +/- 1 years) and 14 older (64 +/- 1 years) participants. Vasomotion was analyzed using a wavelet transform to investigate power of the frequency intervals associated with endothelial, neural, myogenic, respiratory, and cardiac activities of the laser Doppler signal. Laser-Doppler flux increased in both groups with LH (both d > 1.8, p < 0.001). Endothelial activity increased in both groups following LH to 42 C-omicron (young d = 1.4, p < 0.001; older d = 1.2, p = 0.005) and 44 C-omicron (young d = 1.4, p = 0.001; older d = 1.5, p = 0.005). Endothelial activity was higher in the young compared to older group during LH to 42 C-omicron (d = 1.4, p = 0.017) and 44 C-omicron (d = 1.5, p = 0.004). In response to LH to 42 C-omicron and 44 C-omicron, neural activity in both groups was decreased (both groups and conditions: d > 1.2, p < 0.001). Myogenic activity increased in the younger group following LH to 44 C-omicron (d = 1, p = 0.042), while in the older group, myogenic activity increased following LH to 42 C-omicron (d = 1.2, p = 0.041) and 44 C-omicron (d = 1.1, p = 0.041). Respiratory and cardiac activities increased in both groups during LH to 42 C-omicron and 44 C-omicron (All: d > 0.9, p < 0.017). There were no differences in wavelet amplitude between younger and older in the neural (d = 0.1, p > 0.7), myogenic (d = 03.p > 0.7), respiratory (d = 0.4, p > 0,6), and cardiac (d = 0.1, p > 0.7) frequency intervals. These data indicate that LH increases cutaneous endothelial and myogenic activity, while decreasing neural activity. Furthermore, ageing reduces the increase in cutaneous endothelial activity in response to LH. (C) 2017 Elsevier Inc. All rights reserved.