Local thermal sensation and finger vasoconstriction in the locally heated hand

Summary The effects of local heating on finger blood flow (BF) and local thermal sensation (Sens_w) were studied. Finger BFs in both hands were measured simultaneously; one hand was immersed in water the temperature (T_w) of which was raised from 35° C to 43°C by steps of 2° C every 10 min, while the other hand was kept atT_w 35°C. FingerBF in the locally heated hand decreased atT_w 37 to 41°C, while fingerBF in the control hand did not alter. Sens_w, in the heated hand showed a dynamic response, initially increasing concomitantly with an increase inT_w, then gradually returning and adapting to a new level of Sens_w. The dynamic response of Sens_w, was not perceived during mental calculation even whenT_w was raised to 40°C, and the reduction in finger blood flow was not observed. These results suggest that finger vasoconstriction caused by local heating closely relates to the dynamic response characteristic of local thermal sensation atT_w above core temperature, and that the perception of local thermal sensation in the central nervous system is involved in the mechanism of this vasoconstrictor response.