Paradoxical response to water immersion in replanted fingers

When the fingers are immersed in water digital blood flow is reduced and the skin wrinkles, suggesting that vasoconstriction plays a role. However, is wrinkling due to sympathetic activation or some intrinsic property of the skin? To define the role of autonomic innervation in skin wrinkling we measured changes in blood perfusion (Laser Doppler Perfusion Imager) in 20 successfully replanted fingers (mean time after complete amputation 17.5 +/- 5.2 months). We compared responses in replanted fingers with those in corresponding contralateral normal fingers before and immediately after immersion in saline (0.5 mol/l NaCl at 40 degrees C). In the normal fingers, immersion caused a decrease in blood flow by 27.6 +/- 11.5% and skin wrinkling. However, in the replanted fingers blood flow increased by 22.8 +/- 19.6% and the skin did not wrinkle. The paradoxical cutaneous vasodilatation and absence of wrinkling in the denervated fingers suggests that sympathetic innervation is important in water-immersion skin wrinkling.