Parathyroid-Induced Changes in Collagen and Calcium Metabolismin Vivo

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Abstract
The effect of parathyroid extract (PTE) on the metabolism of collagen and calcium was studied with proline-14C and 45calcium. In order to study the effect of PTE on collagen synthesis and bone formation, the labels were injected into rats after 8 days of PTE treatment. Both specific and total radioactivities of hydroxyproline in the total collagen of the bone were higher in the PTE-treated animals, indicating an increased rate of collagen synthesis in bones. The rate of 45Ca deposition into bone was also increased in the treated animals. By contrast, no effect was found in the amounts or radioactivities in the collagen fractions of the skin. In the urine the amounts of hydroxyproline excreted and total radioactivities of hydroxyproline- [registered trademarC were greatly Increased. Mature collagen degradation and bone resorption were studied by injecting PTE Into rats which had received proline-14C and 45Ca 30 days earlier. After 8 days of hormone treatment the urinary excretion of hydroxyproline as well as the specific and total radioactivities of urinary hydroxyproline began to rise. At the same time, there was a great increase in the specific and total radioactivities of 45Ca in the urine. The results suggest that PTE induces increased collagenolysls affecting both collagen precursors and mature collagen in bones. Simultaneously with the lysis of the organic collagenous matrix there occur demineralization and increased synthesis of bone collagen.