[The effects and properties of sodium nucleinate as a pyrogen working standard. 5. Interactions between pyrogens and...

In rabbits, the simultaneous i.v. injection of corticotrophin (ACTH) and bacterial lipopolysaccharide or sodium nucleinate (NN), as well as ATCH application before and after administration of one of the two pyrogens, induces changes in the course of body temperature as compared with other animals injected only one of the pyrogens. Principal differences between the effect of a bacterial lipopolysaccharide and that of sodium nucleinate cannot be observed. At simultaneous pyrogen application, the administration of ACTH leads to a delayed occurrence of temperature increases. Prophylactic ACTH injection induces, if performed only 30 min before pyrogen application, a still greater delay of pyrogen-induced temperature increase, while pyrogens applied 2 h after administration of ACTH induce temperature increases almost immediately. If ACTH is administered after pyrogen application this will at first lead to a temperature reduction, to be followed by repeated increase of temperature so that as a rule temperature curves with two peaks develop. This is true irrespective of whether ACTH application is performed 30, 60, or 90 min after pyrogen administration. Orientation tests have shown that only a part of ACTH present in the test solution can be detected if the biological assay of ACTH is made using the method based on the determination of the ascorbic acid content in the suprarenal glands of prednisolone-treated rats and if one of the two pyrogens simultaneously is applied.