Originally published in Amer. J. Physiol. 180, 325 (1955). 



84. EFFECT OF X-RAYS AND HORMONES ON 

 RESORPTION RATE OF INJECTED NaRi^COg 



A. G. FoRSSBERG and G. Hevesy 



From the Institute Radiophysics, Kaiolinska Sjukhuset, and Institute for Reseai'ch 



in Organic Chemistry, University of Stocldiohn, Sweden 



This paper reports observations on the effect of X-irradiation on the 

 rate of exhalation of ^'^COg by mice, injected with i*C-labelled sodium 

 bicarbonate. The possibility that X-ray effects were mediated through 

 hormonal action led us to investigation of the effects of ACTH as well 

 as of adrenaline, administered alone, or in combination with irradiation. 

 The mean life-time of the bulk of the circulating bicarbonate ions in 

 the body of the mouse being some minutes only, any change in the 

 rate of resorption will be reflected in a corresponding change in the 

 amount of ^^COg exhaled within a few minutes or even seconds after 

 the injection. Following the rate of exhalation of ^^COg is thus a sensi- 

 tive and convenient measure of a changed resorption rate of the intra- 

 peritoneally, subcutaneously or intramuscularly injected labelled bicar- 

 bonate. Such investigations may also supply information on the factors 

 governing the resorption process. 



MATERIAL AND METHODS 



White mice weighing 15—25 gm and fed on standard vitaminized biscuits were 

 injected intraperitoneally, siibcutaneously or intravenously into the tail vein 

 with 0.1 ml of saline containing 10— 50 mgm of labelled sodium bicarbonate having 

 an activity of 0.5—0.3 /uc. A precision "Agla" syringe was used. Each of a group 

 of four mice was placed in a small perforated aluminium box. These boxes were 

 then inserted into a metal cyhnder of 2.5-liter volume throilgh which a C02-free 

 air stream of 150 ml/min passed. The exhalatory COg was led through three cen- 

 trifuge glasses containing a Ba(0H)2 solution. Every 10 minutes the air stream 

 was directed into another set of centrifuge bottles. The precipitated BaCOg was 

 collected, washed and dried. The weight and radioactivity of the precipitate were 

 determined. 



^Vhen following the exhalation of "COg from the start of the injection we 

 used another arrangement, placing each mouse into a brass tube of 4 cm diameter 

 and 15 cm length. The mouse was injected after having been placed into the brass 

 tube through which air passed immediately after the injection which took 15 

 seconds. The air stream carrying the exhalatory COg was diverted every 2 minutes 

 into another set of centrifuge bottles. Contrary to the first described procedure, 



