Abstract
It was shown by Kay 1 that the plasma phosphatase increases in certain clinically observed cases of bone diseases. We have confirmed and extended these observations. 2 In an investigation of experimentally produced bone lesions we have reported the effects of chronic and acute hyperparathyroidism. 3 In view of the many analogies observed in bone resorption, whether produced by parathormone or by other agents, it was desirable to extend our observations to the osteoporoses produced by low-calcium diets and by ammonium chloride administration to animals on low and high calcium diets.
Four litters of dogs were used—3, 6, 8, and 18 months old, respectively. The experiment was continued for about 11 weeks. The animals received a diet of fresh, lean horse meat supplemented with cod liver oil and tomato juice. This is a low-calcium diet. Some of the animals received a calcium supplement (2.5 gm. each of bone meal and calcium lactate per kilo of food) equivalent to between 0.5 and 2.5 gm. of calcium daily. On this diet the controls grew rapidly; the bones were normal upon autopsy. On the low-calcium diet, the growth was equally rapid; the bones, however, were thinned. Ammonium chloride was administered by stomach tube in a 1% solution. At the end of the experiment some dogs received daily as much as 1 gm. per kilo. In the youngest litter bone softening and deformity resulted on a low-calcium diet; in all dogs administration of ammonium chloride generally caused loss of appetite.
The method for determination of phosphatase has been described. 4 , 5 Serum phosphatase rather than plasma phosphatase has been determined in this series of tests to avoid the inhibition of phosphatase activity by oxalate. 5
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