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Cochlear blood circulation studied with microspheres
Abstract:
The cochlear blood flow was studied with the microsphere method in guinea pigs, rats and cats. Results from experiments using different sizes of microspheres were compared and the effect of middle ear infection or perforation of the otic capsule on the cochlear microcirculation was investigated. Neither the opening of the cochlear bony wall nor the middle ear infection influenced the blood flow in the cochlea. 9- and 15-micrometer spheres were given simultaneously and the results were equivalent, indicating no more shunting of the smaller ones than of the bigger ones. Thus, the smaller spheres are to be preferred, since the smaller ones can be used in a larger number without negative effects on the general circulation. In cats, the cochlear blood circulation was determined before and during cervical sympathetic stimulation. Sympathetic stimulation caused a reduction of 25% of the cochlear blood flow.
Insights
Cochlear blood flow is unaffected by middle ear issues or otic capsule damage. Smaller microspheres are preferred for accurately measuring cochlear blood circulation, which sympathetic stimulation reduces.
Area of Science:
- Otolaryngology
- Physiology
- Microcirculation Research
Background:
- Understanding cochlear blood flow is crucial for diagnosing and treating hearing disorders.
- The microsphere method is a common technique for measuring organ blood flow.
- Factors affecting cochlear microcirculation require further investigation.
Purpose of the Study:
- To investigate cochlear blood flow using the microsphere method in guinea pigs, rats, and cats.
- To compare the efficacy of different microsphere sizes for measuring cochlear blood flow.
- To assess the impact of middle ear infection and otic capsule perforation on cochlear microcirculation.
Main Methods:
- The microsphere method was employed to study cochlear blood flow in multiple animal models.
- Experiments involved comparing results from different microsphere sizes (9- and 15-micrometer).
- The effects of induced middle ear infection and otic capsule perforation were examined.
Main Results:
- Neither middle ear infection nor otic capsule perforation significantly altered cochlear blood flow.
- Simultaneous administration of 9- and 15-micrometer microspheres yielded equivalent results, suggesting no significant shunting differences.
- Cervical sympathetic stimulation in cats reduced cochlear blood flow by 25%.
Conclusions:
- The microsphere method is reliable for assessing cochlear blood flow, with smaller spheres being preferable.
- Cochlear blood flow is robust against common middle ear pathologies.
- Cochlear vasculature is sensitive to sympathetic nervous system modulation.