du Boulay G, Darling M
Neuroradiology. 1975 Aug 7;9(3):129-32. doi: 10.1007/BF00332960.
The effects of changes in systemic blood pressure upon external carotid branches of the baboon have been measured by cerebral angiography. They have been shown to have an autoregulatory type of response down to a blood pressure of about 60 mmHg, below which they constrict.