THE INFLUENCE OF EPINEPHRINE ON THE DIGITAL ARTERIOLES OF MAN: A STUDY OF THE VASOCONSTRICTOR EFFECTS

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Abstract
Demonstration of the vasoconstrictor effect of epinephrine on the digital arterioles requires sufficient vasodilatation which may be obtained in the upper extremities (and at times in the lower extremities also) by placing a heat tent over the trunk. This procedure does not impair the vasoconstrictor effect of epinephrine However, even under these circumstances, injection of epinephrine into the veins of patients with normally innervated extremities may not cause significant vasoconstriction. For comparative purposes, the temps. of the skin of the digits of an individual and the temp. of the environmental air must be approximately the same on the different occasions of a study of the effect of injecting epinephrine. Even under these circumstances the results are very variable. In normaity innervated extremities, epinephrine ordinarily produces a slower but more prolonged vasoconstrictor effect in the toes than in the fingers, but there is no constant difference in the magnitude of vasoconstriction in the fingers as contrasted with that in the toes induced by the injection of epinephrine. In subjects with normally innervated extremities, the vasoconstrictor effect of epinephrine on digital arterioles varies widely. Marked variability in the response of the skin temp. of different digits of the same individual and in the response of the skin temp. of the same digit of the same individual on different occasions has been noted. The authors doubt that the response of the temp. of the skin of the digits to the intraven. injection of epinephrine is as reliable a test as has been previously reported. In patients with vasomotor symptoms suggesting Raynaud''s disease. arterioles are not necessarily unduly sensitive to epineph-rine; and great sensitivity of digital arterioles to epinephrine does not necessarily indicate that vasomotor symptoms occur clinically. These observations cast some doubt on the conclusion that the recurrence of vasomotor symptoms after ganglionectomy for Raynaud''s disease is due to increased sensitivity of the arterioles to epinephrine.