Reaction of Skin Blood Vessels to Successive Insults on Normal and Irritated Human Skin

Various physiologic and pathologic processes, including the action of pharmacological substances, depend on histamine as a mediator. The response of irritated or otherwise altered skin to internal and external provocation may differ from the response of intact skin. The effect of histamine may depend on the timing of the sequence of insulting events. Tachyphylaxis, a refractory behavior of histamine receptors of the blood vessels, has been observed in clinical and laboratory studies, but quantitative documentation is lacking.