Possible involvement of capsaicin-sensitive sensory nerves in the regulation of cochlear blood flow in the guinea pig.
Capsaicin-induced microcirculatory changes in the cochlea of anaesthetized guinea pigs were examined by laser-Doppler flowmetry. Close intraarterial capsaicin infusion into the anterior inferior cerebral artery at doses of 10-50 pmol/min was followed by dose-dependent vasodilatation. Capsaicin infused in a dose of 150-200 pmol/min or above resulted in vasoconstriction in the region examined. Topical capsaicin administration into the cochlea (50-150 pmol) resulted in very moderate vasodilation with a latency of 1-2 min. Perivascular capsaicin application onto the anterior inferior cerebellar artery elicited an elevated blood flow in the cochlea, too. It is concluded that the release of vasoactive substances from capsaicin-sensitive nerve fibres in the inner ear of the guinea pig may play a role in the control of the local microcirculation. These nerves may also be involved in the neurogenic inflammatory processes in the region.
Vass
Z
Z
Department of Otohinolaryngology, Albert Szent-Györgyi Medical University, Szeged, Hungary.
Bari
F
F
Jancsó
G
G
D000818:Animals; D001158:Arteries / Q000187:drug effects; D001488:Basilar Artery; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002211:Capsaicin / Q000008:administration & dosage / Q000494:pharmacology*; D002531:Cerebellum / Q000098:blood supply; D003051:Cochlea / Q000098:blood supply* / Q000187:drug effects / Q000294:innervation*; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D007261:Infusions, Intra-Arterial; D017078:Laser-Doppler Flowmetry; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology; D008845:Microinjections; D009412:Nerve Fibers / Q000187:drug effects* / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology*; D010865:Pilot Projects; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D013997:Time Factors; D014661:Vasoconstriction; D014664:Vasodilation
D002211:Capsaicin