PLASMA PROTEIN METABOLISM—ELECTROPHORETIC STUDIES : CHRONIC DEPLETION OF CIRCULATING PROTEINS DURING LOW PROTEIN FEEDING

The findings on electrophoretic analysis of plasma proteins during many weeks of low protein feeding in dogs accord in general with those of chemical analysis as concerns the alterations in plasma albumin and globulin concentrations. Long continued restriction of dietary protein results in decreased albumin levels while plasma globulin concentrations remain essentially normal. The degree of depletion of electrophoretic albumin is, however, considerably greater than that of chemical albumin. When large amounts of protein are fed to such depleted dogs complete restoration of normal plasma albumin concentrations requires several weeks. During these weeks large quantities of nitrogen are retained, presumably as tissue protein reserves. Prompt production of plasma globulin is apparent during such periods. These relationships are more clearly shown in electrophoretic than in chemical analyses and are more conspicuous when only moderate protein intakes are fed. These data may indicate that plasma globulins and certain tissue proteins, in contrast to plasma albumin, enjoy prior demands on the total available pool of body protein materials under emergency conditions. Total electrophoretic globulin areas are increased during depletion. Such increases result largely from elevated alpha globulin peaks and are not disclosed by chemical analysis. They are found to be associated with elevated plasma lipid levels which occur in these depleted dogs. These experiments suggest that in potency tests for dietary protein materials, factors other than the quality of fed protein may influence the relative production of plasma albumin and globulin.