RESORPTION RATE OF INJECTED NaH^'CO, 835 



The resorption of bicarbonate is presumably under hormonal control. 

 This is supported by our finding that a subcutaneous administration 

 respectively of ACTH or adrenaline, markedly changes the rate of resoip- 

 tion of intraperitoneally administered sodium bicarbonate. To some 

 extent also, these hormones influence the exhalation of total COg in 

 the mice. 



As will be found from the Tables 2 A and B, the total amount of COg 

 exhaled in the first 2 minutes varies slightly according to the treatment 

 in each case. It may be argued, then, that these variations in the total 

 amount of COg would influence the corresponding determinations of 

 i^COa. The amount of carrier (Na2C03) added in the latter experiments 

 was, however, equivalent to a precipitate of 200 mgm BaC03. The output 

 of COg in the untreated control group corresponds to about 26 mgm 

 BaC03 during the first 2 minutes. The same figure in the group admi- 

 nistrated ACTH was lower by 18.3% (Table 2A,group2) or about 21 mgm. 

 Thus, the differences in the total amounts of BaCOg received is negligible. 

 The values in the table for 'percentage change in the exhalation caused 

 by treatment' apply, therefore, as well to determinations of the total 

 amount of exhaled ^^COg as to specific activity determinations. 



It appears that the administration of ACTH causes a slight decrease 

 in the total output of COg. In this respect, ACTH acts like irradiation. 

 The rate of resorption of the injected H^^COg is, however, markedly 

 increased and in this respect ACTH acts oppositely to irradiation. It may 

 be considered whether the diminished resorption rate observed in the 

 exposed mouse is due to a blocking effect of the irradiation on ACTH 

 formation. The biological half-life of the injected ACTH is about 5 minutes 

 and the half-life of the ACTH secreted into the circulation may have a 

 similar value. (5) Blocking of ACTH formation through irradiation would 

 manifest itself correspondingly soon. It seems to be in accordance with 

 this hypothesis that an injection of ACTH shortly before irradiation 

 neutralizes the effect of X-rays, as visualized in Table 2A, group 3. 



We investigated also the effect of adrenaline on the rate of resorption 

 of intraperitoneally injected NaH^^COg. An early depression of the 

 amount of "COg exhaled by the adrenaline injected mice was observed 

 (Table 2B, group 1), in accordance with the finding in the X-ray experi- 

 ments (cf. Fig. 1). 



Administration of adrenaline may produce vasoconstriction which 

 depresses the rate of resorption. This was found to be the case when 

 the rate of disappearance of intramuscularly injected ^^Na from the place 

 of injection was measured in human subjects to whom adrenaline had 

 been administered. (6) On the other hand, administration of adrenaline 

 stimulates the formations of ACTH, a substance which favours resorption. 

 Presumably, however, the direct effect of the administered adrenaline 

 may be expected to prevail in our experiment. The decrease in the rate 



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