The contribution of constrictor and dilator nerves to the skin vasodilatation during body heating

During body heating there is a large increase in hand and forearm blood flow owing to vasodilatation mediated by sympathetic nerves. In the forearm the vasodilatation is confined to the vessels of the skin (Barcroft, Bock, Hensel & Kitchin, 1955; Edholm, Fox & Macpherson, 1956; Roddie, Shepherd & Whelan, 1956), and there is some evidence that this is also the case in the hand (Harris, Martin & Williams, 1952). The vessels of the forearm skin are supplied with both vasodilator fibres (Grant & Holling, 1938; Edholm et al. 1956; Roddie, Shepherd & Whelan, 1957) and vasoconstrictor fibres (Roddie et al., 1957). Present evidence indicates that the blood vessels of the hands of normal subjects are supplied only with vasoconstrictor fibres (Arnott & Macfie, 1948; Gaskell, 1956), although the experiments of Lewis & Pickering (1931) suggest that there are vasodilator fibres to the hands of patients with Raynaud's disease. The object of the present experiments was to determine the contribution of vasodilator and vasoconstrictor fibres to the skin dilatation in the upper limb during body heating.