Influence of calcitonin-gene related peptide on cochlear blood flow and electrophysiology

Intra-arterially infused calcitonin gene-related peptide (CGRP) induced dose-dependent decreases in both systemic blood pressure and cochlear blood flow (CBF). However, when subjects were pretreated systemically or locally with the specific receptor antagonist CGRP(8-37), CBF increased, despite decreases in systemic blood pressure in response to CGRP infusions. Micro-infusions of CGRP directly into the supplying arterial network of the cochlea induced dose-dependent increases in CBF that were blocked by CGRP(8-37) pretreatment. Cochlear electrophysiology, as assessed by cochlear action potential and cochlear microphonics, remained unchanged following each condition tested. These results indicate that CGRP is involved in systemic regulation of blood pressure and contributes to the regulation of CBF.