Relation of Plasma Volume to Plasma Protein Concentration

Abstract

It was the purpose of this study to determine the relationship of plasma protein concentration to the plasma volume of non-edematous dogs. The value of plasma albumin determinations in studying fluid exchange has been amply demonstrated. It was consequently determined to perform simultaneous analyses of plasma albumin and globulin concentrations and of plasma volume in dogs that were undergoing certain experimental procedures. The method of Koch and McMeekin 1 was used for determining the plasma protein levels of the first 2 dogs and a micro-kjeldahl procedure involving distillation into N/70 H₂SO₄ and subsequent titration with N/20 alkali was used for the other 2 dogs. The circulating plasma volumes of the first 2 dogs were kindly determined for me by Mr. John Morcan, who used the brilliant vital red technique as described by Whipple and coworkers. 2 Those of the other 2 dogs were performed by the author, utilizing the spectrophotometric procedure for analyzing brilliant vital red described by Clarke and Graff. 3

Changes in the plasma albumin concentration proved to be the most significant ones and consequently they alone will be mentioned in this report.

Two dogs in the anemia colony in this laboratory were studied weekly over a period of 2-3 months. In one of them, both the plasma volume and the plasma albumin concentration remained fairly constant. In the other, as the plasma albumin concentration decreased, the plasma volume decreased. As the plasma albumin concentration increased the plasma volume increased.

Two other dogs (not anemic∗) were placed upon a low protein diet developed by Weech and Goettsch 4 and studied weekly for about 2 months. This diet consisted mainly of carrots and contained essential salts and apparently all of the recognized vitamins.