Experiments with an Isomer of Caffein. 



9 



hours after injection, but tests made one or more days later 

 indicated considerable improvement, and in some cases, recovery. 



4. After the subcutaneous injection of sodium tartrate into 

 rabbits on a diet of oats the time of appearance of the phenol- 

 sulphonephthalein injected was shorter and the duration of the 

 elimination longer than in rabbits which had been receiving carrots. 



5. When sodium tartrate was injected subcutaneously in 

 gradually increasing amounts, no impairment of renal function 

 was observed even with very large doses (4 and 6 grams per kilo) 

 if the diet consisted of carrots exclusively, but the efficiency of 

 the kidney was markedly decreased if oats alone were fed, although 

 the amounts of tartrate administered was only one fourth or one 

 sixth of that given to rabbits on a diet of carrots. 



in (1289) 



Experiments with an isomer of caffein. 



By William Salant and Helene Connet. 



[From the Pharmacological Laboratory, Bureau of Chemistry, U. S. 

 Department of Agriculture, Washington, D. C] 



Physiological tests were made with 1:7: 9-trimethyl-2 : 8- 

 dioxy-purine. Its action was in every respect weaker than that 

 of caffein. The toxicity was about one tenth that of caffein, the 

 minimum fatal dose of 1:7: g-trimethyl-2 : 8-dioxy-purine for 

 frogs being 4.0 to 4.5 grams per kilo. Renal activity as shown by 

 experiments on rabbits, was only moderately stimulated in some 

 cases and was very feeble in others although large doses were given 

 intravenously. Perfusion experiments on the isolated frog heart 

 indicated that an increase in force of cardiac action without altering 

 the frequency may be caused by concentrations of 0.1 and 0.2 per 

 cent, in Ringer's solution, but this effect was never very pro- 

 nounced. 



Prepared and kindly donated to this laboratory by Dr. C. O. 

 Johns of this Bureau. 



