Little is known about the physiologic regulation of the vestibular end
organ blood flow. The purpose of the current study was to examine pos
terior semicircular canal ampulla blood flow in addition to systemic f
actors during intravenous infusions of calcitonin-gene related peptide
(CGRP), a factor involved in the tonic regulation of blood flow. Rece
ptors for this factor are known to be available to the vascular supply
of the vestibular organs. Local blood flow using laser Doppler flowme
try and systemic parameters were monitored during infusion of CGRP, CG
RP antagonists and control vehicle. The results show relatively stable
vestibular blood flow (VBF), concentration-dependent decreases in sys
temic blood pressure, and elevations in heart rate. Pretreatment with
CGRP(8-37), a specific receptor antagonist, attenuated these responses
to subsequent CGRP infusions. These findings suggest a rigid regulati
on of VBF in the presence of a systemically active vasodilator.