Effect of prostaglandin E1 and noradrenalin on cerebrovascular tone and arterial blood pressure

Prostaglandin E₁ (PGE₁), in solution with ethanol, when injected into the carotid artery, increases the tone of the cerebral blood vessels and the arterial blood pressure, whereas PGE₁ without ethanol gives the opposite effect. When PG biosynthesis is blocked by indomethacin, the pressor effect of noradrenalin on the cerebral vessels was considerably increased. It is postulated that PGE₁ is an important component of the system participating in the genesis of cerebral hypertension and determining the character of its course.