Simultaneous Appearance of a Positive Line Test and Radioactive Phosphate Deposition in the Rachitic Rat Metaphysis

Abstract

Following a single dose of Na₂HPO₄ containing the radioactive isotope (P³²) accompanied by a single dose of vitamin D₂, determinations have been made of the radioactive phosphorus content of whole blood and of the tibial diaphysis and metaphysis of rachitic rats. The data show that vitamin D has no influence on the entrance of phosphorus into the blood or into the diaphyseal portion of the tibia. In the metaphysis, however, the healing produced by the vitamin (as shown by the appearance of a positive line test) occurs concomitantly with a significant increase in the content of radioactive phosphorus. These effects in the metaphysis are seen only after the elapse of 54 to 72 hours subsequent to the administration of the vitamin. It is pointed out that the results support the conclusion that the mode of action of vitamin D is not limited to the control of intestinal absorption of the elements concerned in calcification.