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Substance P increases cochlear blood flow without changing cochlear electrophysiology in rats
G M McLaren1, W S Quirk, E Laurikainen
1Department of Psychology, Edinboro University of Pennsylvania 16444.
Hearing Research
|December 1, 1993
Summary
Substance P infusion increases cochlear blood flow (CoBF) in rats, suggesting its role in regulating hearing blood supply. This peptide may be key in maintaining healthy cochlear function through its vasodilatory effects.
Area of Science:
- Oto-neuroscience
- Vascular Physiology
Background:
- Cochlear blood flow (CoBF) is critical for auditory function.
- The role of specific vasoactive peptides in CoBF regulation is not fully understood.
Purpose of the Study:
- To investigate the effect of substance P on CoBF.
- To determine if substance P acts via specific receptors in the cochlea.
Main Methods:
- Substance P was infused into the carotid artery and anterior inferior cerebellar artery of Wistar-Kyoto rats.
- Cochlear blood flow was measured using a laser Doppler flowmeter.
- Auditory potentials and cochlear microphonics were monitored.
- Substance P receptor antagonist was used to block responses.
Main Results:
- Carotid infusions of substance P reduced systemic blood pressure and increased CoBF.
- Direct cochlear artery infusions of substance P increased CoBF without affecting systemic blood pressure.
- A substance P receptor antagonist blocked these vascular effects.
- No changes in cochlear action potentials or microphonics were observed.
Conclusions:
- Substance P, acting through specific receptors, influences cochlear blood flow.
- Endogenous substance P may play a role in the local regulation of CoBF.
- Both vasodilatory and vasoconstrictive mechanisms are likely involved in cochlear blood flow autoregulation.