vasomotor

adj. altering the diameter of vessels (especially blood vessels)

A vasodilator is a drug or chemical that relaxes the smooth muscle in blood vessels, which causes them to dilate. Dilation of arterial blood vessels (mainly arterioles) lead to a decrease in blood pressure.
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Adjective
1. relating to the nerves and muscles that cause the blood vessels to constrict or dilate
(pertainym) vasoconstriction

adj. vasomotor, altering the diameter of vessels (especially blood vessels)

(a.)
Causing movement in the walls of vessels; as, the vasomotor mechanisms; the vasomotor nerves, a system of nerves distributed over the muscular coats of the blood vessels.