Concentrating ability of lymphatic vessels.

The fluid from implanted capsules was analyzed for plasma proteins and compared with fluid sampled from small lymphatics which drained the region of the implanted capsules. The plasma protein concentration of capsular and lymphatic fluids were not found to be statistically different, for capsules implanted for greater than one month. Capsules implanted for less than one month demonstrate a much higher total protein than lymphatic fluid. This difference is thought to be due to several factors: (1) length of time that capsule has been implanted, (2) inflammation surrounding capsule, (3) time lag between sampling of lymphatic and tissue fluids. If capsules were used that had been implanted for greater than 1-1/2 months, then capsular and lymphatic fluids are not statistically different. A model is presented which predicts that the small initial lymphatics could or could not concentrate plasma proteins depending on the fate of the leaked fluid. The concentrating ability of the initial lymphatics will depend on whether or not the fluid leaked from the initial lymphatic is large relative to the surrounding volume, the time course of protein diffusion to the vicinity of the lymphatic and the rate of fluid removal from the space immediately surrounding the lymphatic. While there is a distinct possibility, since the forces exist, for a concentrating mechanism in larger lymphatic vessels, the data from implanted capsules indicate that we can assume that lymphatic vessels, especially in the subcutaneous region, contain plasma protein concentrations that are fairly representative of the tissue fluids of that region.