Which of the following is NOT the role of histamine in acute inflammation?
Vasodilation is the most impoant vascular effect of histamine in humans. It involves both H1 and H2 receptors distributed throughout the resistance vessels in most vascular beds. Histamine's effect on small vessels results in efflux of plasma protein and fluid into the extracellular spaces and an increase lymph flow, causing edema. The gaps between endothelial cells also may permit passage of circulating cells recruited to tissues during the mast cell response. In the epidermis, it causes itch; in the dermis, it evokes pain, sometimes accompanied by itching. Also know: Triple Response of Lewis: If histamine is injected intradermally, it elicits a characteristic phenomenon known as the triple response. This consists of: A localized red spot within a few seconds and reaches a maximum in 1 minute. A brighter red flush, or "flare," extending around 1 cm developing more slowly. A wheal that is discernible in 1-2 minutes. The initial red spot results from the direct vasodilating effect of histamine (H1 receptor-mediated NO production). The flare is due to histamine-induced stimulation of axon reflexes that cause vasodilation indirectly. The wheal reflects histamine's capacity to increase capillary permeability (edema formation). Ref: Skidgel R.A., Erdos E.G. (2011). Chapter 32. Histamine, Bradykinin, and Their Antagonists. In L.L. Brunton, B.A. Chabner, B.C. Knollmann (Eds), Goodman & Gilman's The Pharmacological Basis of Therapeutics, 12e.
It mediates increase in vascular permeability
It mediates chemotaxis
Release of pain causing substances
Causes vasoconstriction