Originally published in Acta Physiol. Scand. 35, 846 (1955). 



85. NOTE ON THE EFFECT OF X-RAYS AND HORMONES 

 ON THE RESORPTION RATE OF INJECTED NaH"C03 



A. FoRSSBERG and G. Hevesy 



From the Institute of Radiophysics and the Institute for Research in Organic 



Chemistry, Stockholm 



In a previous communication (Forssberg and Hevesy, 1955), evidence 

 was presented for an effect of exposure to X-rays on the rate of resorption 

 of injected i*C-labelled sodium bicarbonate as indicated by the rate 

 of exhalation of ^^COg. The circulating bicarbonate in the body of the 

 mouse has a mean life-time of a few minutes only and consequently 

 any change in the resorption rate will be indicated by a corresponding 

 change in the amount of exhaled ^^COg within the first minutes after 

 the injection of the labelled bicarbonate. 



The percentage ^^COg exhaled by irradiated mice in the first 4 minutes 

 following injection was found to be 29% of the amount administered 

 which compares with 45% exhaled by the non-irradiated controls. In a 

 later stage of the experiment as in the 6 — 10 min time interval, the 

 amount of ^^COg exhaled by the exposed animals was found to be larger 

 than that exhaled by the controls as the early preferential exhalation 

 by the controls led to an accumulation of -^^COa by the exposed mice. 



An X-ray effect did not manifest itself when administering the bicar- 

 bonate by intravenous injection. As the effect observed may have been 

 mediated through hormonal action on the resorption process, we investi- 

 gated the effect of both adrenaline and ACTH-administration on ^^COg 

 exhalation. Subcutaneous injection of adrenaline was found in our pre- 

 vious investigation to decrease the rate of exhalation of ^^CO, in a similar 

 way as did irradiation, whereas injection of ACTH increased the imme- 

 diate output of ^^COg. Experiments in which exposure to radiation and 

 hormonal treatment were combined brought out that an ACTH injection 

 given shortly before irradiation annihilates the effect of the latter. The 

 last mentioned observation can possibly be explained by an immediate 

 depressive effect of X-irradiation on the resorption of NaHi^COg due to 

 a momentary blockage of the release of ACTH. The combined effect of 

 an adrenaline injection and irradiation had the unexpected effect that 

 the initial output of ^^COg was much higher than that from control mice 

 although each agent alone caused a depressed ^^COg exhalation. The 

 mechanism inherent in this synergistic action is obscure. 



