The purpose of the present study was to determine whether selective ac
tivation of vestibular receptors produces changes in blood pressure. B
lood pressure was recorded during trapezoidal head rotations in cats w
ith extensive denervations to eliminate nonlabyrinthine inputs that co
uld be produced by the movements. Large (50 degrees) nose-up trapezoid
al head tilts produced an increase in blood pressure of approximately
18 mmHg; ear-down tilt produced little change in blood pressure. The c
hanges in blood pressure began approximately 1.4 s after the plateau o
f the stimulus. The responses to nose-up tilt were abolished following
intracranial transections of the VIIIth cranial nerves. These data su
ggest that vestibular inputs elicited by nose-up movements of the head
act to rapidly increase blood pressure. This mechanism may contribute
to counteracting the orthostatic hypotension induced by nose-up body
rotation in quadrupeds.