Amount of albumin and its mixing rate in the dog

¹ Departments of Physiology, Baylor University College of Medicine and The University of Texas Dental Branch, Houston, Texas

Data on rates of mixing of I¹³¹-tagged albumin between vascular and extravascular compartments indicate that albumin disappears from the plasma at three exponential rates. The first rapid rate changes to a slower rate at 8 hr and continues until mixing is complete between vascular-extravascular albumin, in approximately 3 days. The third rate is interpreted as the metabolism of albumin. The data suggest that the extravascular space has at least two compartments, one that exchanges albumin with plasma rapidly and the other slowly. At approximately 8 hr, equilibrium was reached between specific activity of plasma and lymph albumin; it was postulated that the rapidly mixing extravascular compartment may be associated with the large pore area of the liver. Total amount of albumin was 2.87 g/kg with a ratio of extra- to intravascular albumin of 1.22. The mean volume of distribution of albumin was 168.8 ml/kg (17% of body wt), with 50 ml/kg in the circulation, 15.3 ml/kg in the rapidly mixing, and 103.5 ml/kg in the slowly mixing compartments of extravascular spaces.

Key Words: albumin distribution • albumin space in the dog • albumin mass in dogs • volume distribution of albumin • albumin exchange • exchange rate of albumin • albumin mixing rate • plasma-lymph albumin • extravascular/vascular albumin

Submitted on May 25, 1964