582 B. K. rORSCHER AND D. V. COIIN 



to its specific physiologic action. A second possibility is that the 

 metabolic effect was secondary to the abnormally high concentra- 

 tion of serum calcium associated with treatment with the parathyroid 

 hormone. To rule out the first possibility, we performed experiments 

 similar to those performed with slices of bone, ])ut used instead slices 

 of kidney, liver, and muscle. Kidney is also a target organ of para- 

 thyroid hormone, and results were similar to those obtained with 

 bone (Table III). Other tissues from the same animals, such as liver 

 and muscle, did not produce the CO2 effect (Table III). 



TABLE II L Effect of Parathyroid Extract on Production of €^■^02 

 BY Kidney' and Other Tissues 



The second possibilitv was examined in two ways : bv experiment- 

 ing with rabbits whose concentration of serum calcium had been 

 artificially maintained at a high level, and bv experimenting with 

 parathyroidectomized rats. 



In the first of these studies an increased concentration of serum 

 calcium was maintained in rabbits with subcutaneous injections of 

 a neutral suspension of calcium chloride in olive oil. After 6 hours, 

 these animals and their controls were sacrificed. In vitro metabolic 

 studies were then carried out on samples of bone and kidney. The 

 data (Table IV) show two important findings. One is that the high 

 calcium levels in the serum do not affect the metabolic pattern of 



