Comparison of non-irradiated and irradiated cholesterol to inhibit the hemolytic action of digitonin.

Abstract

As is well known, digitonin exerts a hemolytic action on red blood corpuscles, and cholesterol has the power to inhibit this activity. In view of the fact that our experiments have shown that the chemical properties of cholesterol are altered in various ways as the result of irradiation with ultra-violet light, it seemed worth investigating whether its property of inhibiting the action of digitonin remained unchanged after irradiation.

A comparison was made of the effect, in relation to hemolysis, of ordinary cholesterol with that of cholesterol which had been irradiated for periods of 1/2, 2 and 10 hours with the radiation of a mercury vapor lamp, set at a distance of 1 foot. For this purpose a suspension of 1 per cent ethereal solution of cholesterol and 0.1 per cent digitonin was tested on the red cells of the dog and of the sheep. Without going into detail at this time, it may be stated that it was found that the rate of speed with which the cholesterol bound the digitonin had been altered as the result of irradiation—that the irradiated cholesterol bound digitonin more readily than ordinary cholesterol, and brought about a comparative delay in its hemolytic action. For example, whereas under controlled and constant conditions ordinary cholesterol allowed complete hemolysis to take place immediately, when cholesterol was used which had been irradiated for 2 hours, complete hemolysis did not occur until after an interval of 1 1/2 to 3 minutes. The sterol-digitonin was incubated for 3 hours before it was added to the red cells. When, however, the cholesterol was irradiated for a prolonged period, for 10 hours, this delay did not take place and complete heniolysis occurred immediately.