Calcium Balance of the Blood. 



165 



78 (1660) 



The effects of citrates, malates and phosphates upon the calcium 

 balance and the calcium content of the blood. 



By GUY W. CLARK (by invitation). 



[From the Department of Biochemistry and Pharmacology, University 

 of California, Berkeley.] 



Most of the literature concerning the action of the citrates, 

 malates, phosphates deals with the toxicity, tolerance, excretion 

 and cumulative effects of these substances. The experiments 

 briefly presented in this paper were carried out to ascertain whether 

 the repeated administration of various acid radicals, commonly 

 classified as "calcium precipitants," would, (1) result in a perma- 

 nent decrease of the calcium content of the blood and, (2) if the 

 calcium balance would be affected in any way. 



Rabbits receiving a calcium-rich diet (daily intake of 0.44-1.24 

 gm. of Ca 1 were used as experimental animals. The calcium 

 balance was determined at weekly intervals; the calcium content 

 of the whole blood and plasma at intervals of 3-7 days. 



Citrates 



Five rabbits received 5-45 daily (subcutaneous) injections of 

 0.26-1.23 gm. per kg. of one of the following: tri-sodium, tri- 

 potassium, di-sodium citrate and citric acid. The experiments 

 show that all of the animals maintained a highly positive balance 

 and that there were no abnormal variations in the calcium content 

 of the blood. On the first day of the injection period one animal 

 received (during i}4 hours) two subcutaneous doses (50 c.c. each) 

 of 4 per cent tri-sodium citrate. Thirty minutes after the second 

 dose the plasma showed a decrease of 14 per cent, in its calcium 

 content. Four days later the same animal received two doses 

 (50 and 55 c.c.) of the same solution of sodium citrate. Thirty 

 minutes after the first injection the plasma showed a decrease of 16 

 per cent, in its calcium content. Autopsy was performed on three of 

 the animals and no macroscopic lesions of the urinary system 

 were found. Polyuria was a usual result — definite diuresis was 

 observed in only one case. 



See under Phosphate for exceptions. 



