Parathyroid hormone and release of calcium 45 from bone

¹ Department of Biochemistry, University of Illinois College of Medicine, Chicago, Illinois

An attempt was made to determine from which compartment of bone the calcium is released under the influence of parathyroid hormone. To do this, rats were raised on a homogeneous diet containing calcium 45. When the calcium of the bones and blood had the same specific activity as the diet, the rats were maintained on a normal nonradioactive diet until the specific activity of the different compartments were grossly different. Parathyroid hormone was then administered intraperitoneally, and the changes in specific activity of bones and serum were measured. The results show the increase in serum calcium following hormone treatment does not come entirely from the rapidly exchangeable compartment, but rather that parathyroid hormone also affects the slower exchanging fraction bone.

Key Words: bone resorption in rats • bone calcium compartments • calcium 45 exchange

Submitted on March 12, 1963

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