564 



Co 

 % 



I 20 



G. NICHOLS, JR. 



100 



90 



80 



7 -L 



CONTROLS 



PT E 



Fig. 4. Components of the "steady state" Ca++ concentration maintained 

 by bone samples (calvaria) from normal and parathyroid-treated mice after 

 6 hours' incubation. Parathyroid-treated animals received 0.15 ml Lilly para- 

 thyroid extract subcutaneously daily for 3 days prior to sacrifice. Conditions 

 of incubation, etc., were the same as for Figs. 2 and 3. The fraction denoted 

 "solubility" was taken as the concentration maintained by heat-inactivated 

 samples (cf. Fig. 2). All data are plotted as percentages of the values obtained 

 using fresh bone from normal animals in a complete medium. (This diagram 

 has been reproduced from Schartum and Nichols, 1961/^, with the permission 

 of the Journal of Clinical Investigation.) 



Schartum and Nichols, 1961a) using Uving bone from animals treated 

 with other agents known to affect Ca metabolism have provided 

 further support for this view. The results of these experiments are 

 contrasted in Fig. 5 with those of the parathyroid experiments. These 

 data indicate that vitamin D treatment causes an increase in both 

 Ca and P, parathyroid extract an increase in Ca only, and cortisone 

 no change in Ca but a notable depression of P. Although not shown 

 in the diagram, the vitamin D effects — as in the parathyroid experi- 



