Protein metabolism and exchange as influenced by constriction of the vena cava; experimental ascites as internal plasmapheresis; sodium chloride and protein intake predominant factors.

Constriction of inferior vena cava above the diaphragm is used to produce experimental ascites in the dog. This type of experimental ascites drains the body protein reserves, reduces the level of circulating plasma proteins, and in effect is an internal plasmapheresis. As the ascitic fluid is withdrawn and the proteins measured, we observe a production of ascitic protein (80-90 gm. per week) comparable to that removed by plasmapheresis (bleeding and replacement of red cells in saline). High protein diet tends to decrease the ascites but the protein content of the ascitic fluid may increase. Sodium chloride increases notably the volume of the ascites which accumulates and the total ascitic protein output increases. Sodium-free salt mixtures have a negative influence. High protein diet low in sodium salts gives minimal ascitic accumulation under these conditions. The question of circulation of the ascitic fluid is raised-how rapid is the absorption and the related accumulation?