Abstract
Eight adult dogs were given intraperitoneal injections of 2.5% dextrose and 0.9% NaCl solution in the dosage of 100 cc per kg. After 16 hours, 20 cc of blood were withdrawn from the femoral artery and 20 cc of fluid from the peritoneum. Five hundred units of parathyroid hormone 4 were then injected intramuscularly. Similar blood and fluid samples were obtained hourly for 8 hours and were examined for Ca, Mg and inorganic P content.
Magnesium. The control values for serum Mg were 2.1-3.26 mg %. In 6 cases parathyroid administration was followed by a fall in serum Mg, the maximum decrease being 0.35-0.8 mg % at 1-6 hours, with a tendency to return to normal at 3-8 hours. In one case the serum Mg increased (0.3 mg). No significant change occurred in one case.
The control values for peritoneal fluid Mg were 1.75-2.0 mg %. These increased in each instance, the maximum increase being 0.17-1.02 mg %, the peak occurring at 5-8 hours. The control ratio of fluid to serum Mg was 57-87%, the mean being 75%. This ratio rose in each case, the maximum rise being 12-46% at 5-7 hours.
The relatively slight changes in serum Mg after parathyroid hormone administration are in accord with previous reports. 1 , 2 , 3 However, these described a primary increase in serum Mg followed by a decrease, whereas the opposite occurred in the majority of animals in the present series. The most consistent change was an increase in the amount of diffused Mg, suggesting that the parathyroid hormone increases the diffusibility of serum Mg.
Inorganic P. Control values for serum P were 3.1-5.4 mg %. These fell in every case after parathyroid administration, the maximum decrease being 0.6-1.1mg.
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