THE VASOMOTOR COMPONENTS IN THE VASCULAR REACTIONS IN THE FINGER TO COLD

Abstract

Vascular reactions in the finger to chilling were examined by means of the photoelectric plethysmograph. The initial immediate constriction on application of cold is due to vasoconstrictor reflexes on which is superimposed somewhat later the direct constrictor action of cold. Accompanying constriction occurs also in the warm control fingers of the same and opposite hands, but the constriction is usually more intense in the chilled finger; if a vasoconstrictor reflex is not elicited in the control fingers by an application of moderate cold, the constriction in the chilled finger occurs in a gradual progressive manner, as in the forehead skin, due to the direct constrictor effect of cold on these vessels. The reactive dilatation, which follows in the chilled finger within 3-8 min. after the application of cold, occurs independently of the vasomotor system. The dilatation may be limited to the chilled finger and may occur there when the vasoconstrictor tone is high in the control fingers; vasoconstrictor reflexes were elicited in the chilled finger during the reactive dilatation in some expts., while in other instances definite evidence of vasoconstrictor paralysis in the chilled finger was obtained.