Proteases and the Depletion and Restoration of Skin Responsiveness to Radiation

Abstract

THE intravenous injection of a vital dye (pontamine sky blue, 1.2 ml. of 5 per cent solution/kg body-weight) immediately after local irradiation of a rabbit's skin (1,000 r., 60–140 kV) is followed within a few minutes by an intense blueing of the irradiated area, allowing the investigation of tissue events hitherto unnoticed in the so-called latent period. This circumscribed leakage of dye in the early phase of inflammation is abolished if the animals are pretreated with total or partial body irradiation (400 r., 230 kV, half-value layer = 1.8 mm Cu) or systemically with alkylating agents, and also with softer radiations used in order to avoid effects on deep-seated organs. This unresponsiveness is temporary, as the restoration of local reactivity occurs within six days in the experimental conditions described1.