Vasoconstrictor

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A vasoconstrictor, also vasopressor and simply pressor, is any substance or that acts to cause vasoconstriction (narrowing of the lumena of blood vessels) and usually results in an increase of the blood pressure. The opposite process, vasodilation, is the opening of blood vessels.

Many vasoconstrictors act on specific receptors, such as vasopressin receptors or adrenoreceptors. Vasoconstrictors are also used clinically to increase blood pressure or to reduce local blood flow. Exposure to moderately high levels of stress also induces vasoconstriction.

Vasoconstriction also occurs in superficial blood vessels of warm-blooded animals when their ambient environment is cold; this process diverts the flow of heated blood to the center of the animal, preventing the loss of heat.