Vascular permeability to plasma, plasma proteins, and cells: an update.
OBJECTIVE
The blood vasculature supplies tissues with nutrients, clears waste products, and carries and directs leukocytes to inflammatory sites. To accomplish these functions, microvessels regulate the extravasation of small molecules, plasma proteins and inflammatory cells. The mechanisms responsible for these events have been the subject of intense investigation and, often, dispute.


RESULTS
Recent progress has contributed to a better understanding of the mechanisms by which microvessels of different types and in different vascular beds regulate the passage of small and large molecules and cells. Roles are shown for the glycocalyx, caveolae, perictyes, sphingosine-1-phosphate, and newly discovered signaling pathways.


CONCLUSIONS
Vascular permeability is important for maintaining homeostasis and is greatly increased in acute and chronic inflammation, wound healing, and growing tumors. New work has contributed importantly to the mechanisms responsible for regulating permeability.
Dvorak
Harold F
HF
Center for Vascular Biology Research and the Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA. hdvorak@bidmc.harvard.edu
D000818:Animals; D001798:Blood Proteins / Q000378:metabolism*; D001808:Blood Vessels / Q000502:physiology*; D002199:Capillary Permeability / Q000502:physiology*; D002463:Cell Membrane Permeability; D006801:Humans; D015398:Signal Transduction
D001798:Blood Proteins