pressor

(noun) any agent that causes a narrowing of an opening of a blood vessel: cold or stress or nicotine or epinephrine or norepinephrine or angiotensin or vasopressin or certain drugs; maintains or increases blood pressure. Synonyms: vasoconstrictor, vasoconstrictive.

(adj) increasing (or tending to increase) blood pressure. Example: "Pressor reflexes."