Abstract
Approximately 90% of the calcium may be adsorbed from the serum of normal dogs by shaking with solid Pb3(PO4)2. 1 Using this method of decalcifying blood the following experiments have been carried out.
Small dogs were alternately bled maximally (about 50% of their blood volume) and immediately transfused with an equal volume of decalcified blood. This procedure was repeated as many as 28 times in the course of an afternoon. Each sample of blood removed was analyzed for calcium, phosphorus, and occasionally for CO2 and pH. When the transfusions were repeated every 20 minutes the serum calcium did not decrease below 2.1 millimols per liter and no symptoms occurred.
When only 10 minutes were allowed to elapse between transfusions the serum calcium decreased to 1.6 millimols per liter after 12 or 13 transfusions. Mild symptoms of tetany appeared when the serum calcium reached 1.75 millimols per liter (7 mg. per 100 cc.). These persisted as long as the serum calcium was kept below this level. If an interval of 20 minutes or longer was allowed to elapse between transfusions the serum calcium rose promptly, even though the calcium removed had far exceeded that calculated as being initially present in solution in the body. This is interpreted as evidence that the bone salts are freely soluble in serum which has been rendered undersaturated with respect to them. Experiments of this nature were performed on 6 normal dogs. The cerebrospinal fluid was analyzed for its calcium content at the end of the experiment in one dog and was found to be 1.6 millimols per liter, a normal value.
The symptoms observed may be characterized as those of a mild tetany. At no time did a well-defined convulsion occur.
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