Ultra-violet radiation and metabolism, with a new method for estimating metabolism

Abstract

The effects of from 1 to 11/2 hours'' irradiation by certain groups of rays from the mercury vapor lamp upon the O2 consumption and the CO2 production were studied employing human subjects, white mice, and white rats. The groups of rays tested were 223-770[mu][mu], 290-436[mu][mu], 400-770[mu][mu], and 400-436[mu][mu], the screens employed being ordinary glass and blue uviol. No effects upon metabolism either during or after the irradiation were observed. The metabolism of the human subjects was estimated by the Douglas-Haldane method. Only about 5% of the body surface (front or back of trunk) was exposed. The rats and mice were fully exposed but unshaven, the CO2 output being estimated sometimes by the Haldane-Pembrey method. Since the O2 consumption could not be estimated by the Haldane-Pembrey method a new circulation method was introduced. The animals were placed in an air-tight chamber just large enough to hold them. With a rat of about 100-120 gm., about 20 liters of air were circulated through the chamber by means of a pump and valves, at the rate of 700 cc. per minute. The greater part of the air was held in a small collapsible bag with suitable inlet and outlet tubes. At the end of an hour this bag was disconnected and its contents analyzed for CO2 and O2. O2 fell in 1 hour''s 1 rebreathing to about 19.4% and the CO2 content of the air was 1.0%. Changes of this degree in the CO2 and O2 content of the air are known to have no effect in themselves upon metabolism. The method gave results similar to those with the Haldane-Pembrey method and is both simple and handy for small rats and groups of mice.