On the active vascular absorption of plasma proteins from tissue: rethinking the role of the lymphatic system.
According to Starling's hypothesis, the osmotic pressure of plasma proteins in the capillary is the principal force for fluid absorption. The leakage of plasma proteins from capillaries to tissue during 24 h accounts for the total amount of plasma proteins in the vascular system. The same amount must therefore be reabsorbed by the lymphatic system, which is considered to be the sole absorber of proteins from tissue. However, it is a well-established routine in all kinds of organ transplantation to not restore the lymphatic system of the transplant. Experience has shown that this reconstruction is unnecessary, which consequently implies that the lymphatics are not of crucial importance for the survival of the organ. Inevitably, we must therefore question the vital role that the lymphatic system has been attributed in maintaining homeostasis as the sole absorber of proteins. Instead, it is proposed that the major part of plasma proteins in tissue is actively absorbed by the capillaries.
Greitz
Dan
D
Department of Neuroradiology, MR-Research Center, Karolinska Hospital, Stockholm, Sweden. dan.greitz@ks.se
D000042:Absorption; D001692:Biological Transport; D001798:Blood Proteins / Q000378:metabolism*; D002196:Capillaries / Q000502:physiology; D004730:Endothelium, Vascular / Q000502:physiology*; D006801:Humans; D008208:Lymphatic System / Q000502:physiology*; D008209:Lymphedema / Q000097:blood / Q000503:physiopathology; D008955:Models, Cardiovascular; D009131:Muscle, Smooth, Vascular / Q000502:physiology*
D001798:Blood Proteins