Plasma Proteins and Edema

Abstract

In health, about four fifths of the solids of the plasma consist of plasma proteins. Their approximate percentages are as follows: total protein, from 7 to 8; albumin, from 4 to 5; globulin, from 1.5 to 3.5; fibrinogen, from 0.1 to 0.25; albumin-globulin ratio, 37.The colloidal osmotic pressure of the blood plasma is from 25 to 30 mm. of mercury and is maintained largely by the plasma proteins, as was first revealed by Starling.1 The colloidal osmotic pressure of the blood plasma (the totality of pressure with which the colloid tends to retain water) is not necessarily proportional to the total concentration of plasma protein, because the individual plasma proteins have different colloidal osmotic pressures. The total amount of protein may remain the same, while variations of the relative proportions of the different proteins may change the osmotic pressure. The colloidal osmotic pressure exerted by the smaller molecular complex of albumin is much greater than that exerted by the larger complex of globulin. Fibrinogen, which has a still larger molecular complex, exerts a still smaller pressure.2 Starling 1 pointed out that since the normal capillary wall is imper¬ meable to the plasma proteins, their colloidal osmotic pressure (attraction of the plasma proteins for water) must tend to counteract transudation from the capillaries and aid absorption from the tissue spaces. The hydrostatic (hydraulic) pressure, which is higher in the arteriolar than in the venous end of the capillary, favors transudation, opposes absorp¬ tion and tends to force fluid out into the tissue spaces. Under healthy conditions, an equilibrium between the transudation and absorption obtains. Any factor markedly altering the colloidal osmotic pressure,

The Plasma Proteins and Cardiac Oedema

“…and it has been suggested that it may be correlated with an effort of the organism to compensate for the decrease in osmotic pressure following the loss of serum protein (FISHBERG). This, however, has not been confirmed and CALVIN and GOLDBERG (24) who, in children presenting the nephrotic syndrome, found in general that as the oedema increased the cholesterol increased and the albumin decreased, are not prepared to subscribe to the idea that the increased blood cholesterol is a compensatory mechanism in view of the variations observed. There is thus no direct evidence that the lipaemia has any relation to oedema, and on the whole HILLER's suggestion seems the most probable.…”

“…One such theory is that advanced by CALVIN and GOLDBERG (24) who postulate some °trigger, mechanism of unknown origin,"…”