vasopermeability reactionPhysiology An inflammatory response to local ↑ in vasomotor substances, which evoke egress of fluids and cells from the vascular compartment during inflamation. See Slow-reactive substances of anaphylaxis, Triple response, Vasculitis.
Vasopermeability reaction–phases of
Immediate-transient response mediated by histamine, as well as leukotriene E4, serotonin, bradykinin and others, a reaction affecting small (< 100 µm in diameter) venules, but not capillaries; during this phase, the endothelial cells contract, widening the interendothelial cell gaps
Immediate-sustained response follows severe injury, eg burns and is associated with endothelial cell necrosis, affecting the small arterioles, capillaries and venules and
Delayed-prolonged leakage begins after a delay of hours to days, representing a response to a vast array of environmental 'toxins', eg burns, bacterial toxins, UV light, and X-rays and delayed hypersensitivity reactions, which affect venules and capillaries