Increased subcutaneous adipose tissue blood flow in UVB-inflamed human skin. The existence of a cutaneous-subcutaneous reflex mechanism?

In 4 healthy subjects a skin area 10 mm in diameter was exposed to twice the minimal erythema dose of UVB. Subcutaneous blood flow (SBF) in the area was measured by the local 133-Xenon washout technique before and 8, 24, 48 and 72 h after induction of inflammation. Local skin temperature (TS) was monitored with electrical thermocouples. SBF gradually increased by 400% and peaked 24 to 48 h after induction of inflammation, while TS peaked after 8 h (+3 degrees C). The disparity in skin temperature and subcutaneous blood flow indicates that TS is not the governing factor in the increase in SBF. As release of inflammatory mediators from the cutis influencing the subcutis and a local effect of UVB on subcutis are unlikely, we suggest the existence of a cutaneous-subcutaneous vascular reflex mechanism as an explanation for the increased subcutaneous blood flow.