Pressor response elicited by nose-up vestibular stimulation in cats.

The purpose of the present study was to determine whether selective activation of vestibular receptors produces changes in blood pressure. Blood pressure was recorded during trapezoidal head rotations in cats with extensive denervations to eliminate nonlabyrinthine inputs that could be produced by the movements. Large (50 degrees) nose-up trapezoidal head tilts produced an increase in blood pressure of approximately 18 mmHg; ear-down tilt produced little change in blood pressure. The changes in blood pressure began approximately 1.4 s after the plateau of the stimulus. The responses to nose-up tilt were abolished following intracranial transections of the VIIIth cranial nerves. These data suggest 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.