Relationship between cochlear blood flow and perilymphatic oxygen tension

Kawakami, Michiro; Makimoto, Kazuo; Noi, Osamu; Takahashi, Hiroaki

doi:10.1007/bf00627635

Cited by 9 publications

(3 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…BP showed marked increases on administration of NA or NPY. Several reports have suggested that the changes in CBF depend on changes in BP (13,14) and so in this study the normalized value of the CBF was examined, which has been reported to be a useful parameter for evaluating changes in CBF (15). The normalized CBF increased soon after infusion of NPY, and then decreased rapidly to below the baseline level.…”

Section: Discussionmentioning

confidence: 99%

Effects of Neuropeptide Y on Cochlear Blood Flow in Guinea Pigs

Itou

Ogawa²,

Inoue³

et al. 2001

Acta Oto-Laryngologica

View full text Add to dashboard Cite

The aim of this study was to clarify the effects of neuropeptide Y (NPY) on cochlear blood flow (CBF) in pigmented guinea pigs. NPY was administered with or without noradrenaline (NA) by systemic perfusion or perilymphatic local perfusion, and CBF was measured using a laser Doppler flowmeter. The systemic and perilymphatic administrations of NPY with NA induced greater prolongation of the increase in and recovery of CBF than the administration of NA or NPY alone. Continuous reduction in CBF induced by NPY may play an important role in the pathogenesis of stress-induced sensorineural hearing losses, such as sudden deafness.

show abstract

Section: Discussionmentioning

confidence: 99%

Effects of Neuropeptide Y on Cochlear Blood Flow in Guinea Pigs

Itou

Ogawa²,

Inoue³

et al. 2001

Acta Oto-Laryngologica

View full text Add to dashboard Cite

show abstract

“…Until the last decade most of these proposals were at best speculative because data on IEBF were meager. More recently, techniques have been developed to permit dynamic, precise, and quantitative measurement of the IEBF 8 , 9 ; in particular, the development of laser Doppler flowmetry (LDF) 10 has led to widespread development of laboratories for the studies of cochlear BF (CBF) (e.g., Scheibe et al, 11 Laurikainen et al, 12 Dengerink et al, 1 , 3 Quirk et al, 14 Nakashima et al, 15 Kawakami et al, 16 and Jung et al 17 , 18 ).…”

Section: Figurementioning

confidence: 99%

Studies of inner ear blood flow in animals and human beings

Miller

Ren

Nuttall

1995

Otolaryngol.--head neck surg.

View full text Add to dashboard Cite

This article reviews current studies on inner ear blood flow, discusses their relevance to the maintenance of normal homeostasis of the inner ear, reports for the first time clear changes in fundamental properties of cochlear blood flow in the chronic hydropic ear, and describes the potential of applying laser Doppler flowmetry technology to the measurement of inner ear blood flow in human beings. Studies of the guinea pig in which perfusion pressure is varied demonstrate a broad range of autoregulatory capabilities of the inner ear vasculature. Gain factors range from 0.76 and higher for recovery for less than 1 minute of modified perfusion pressure. This is significantly greater than reports obtained for brain autoregulation. In a series of four investigations of cochlear blood flow in the hydropic ear in guinea pigs, a decreased responsiveness to electrical stimulation and direct stimulation of the superior cervical ganglia was found, indicating a change in sympathetic control of cochlear tone. Reduced vasomotion was observed, and autoregulatory capabilities were reduced. In human investigations, changes in cochlear blood flow were demonstrated with direct electrical stimulation of the round window and warm water irrigation of the ear canal, but not with carbogen breathing. Increased cochlear blood flow was observed with increased systemic blood pressure, and a remarkable decrease in cochlear blood flow was observed with the application of 1:10,000 epinephrine to the round window. These observations indicate the potential for development of laser Doppler flowmetry technology in the diagnosis and treatment of inner ear vascular disorders, and the animal Investigations suggest that changes may occur in the chronic hydropic ear that compromise autoregulation and thus increase the sensitivity of the hydropic ear to other stress factors. Treatments can be found to modify such changes in vascular tone.

show abstract

“…Since PCF in the stria vascularis is dependent on the CoBF, the level of EP during hypoxemia could be elevated by the in creased CoBF even when the lowered O2 saturation in the circulatory blood is kept in the same concentration during the hypoxemia. This suggests that for patients with partial hearing impairment due to acute hypoxemia, treatment to augment CoBF by elevating systemic blood pressure or by the administration of vasoactive agents would be effective [17] . In the hyperventilation experiment of the present study, EP did not show any significant change during and after hyperventilation.…”

mentioning

confidence: 99%

Effects of Hyperventilation and Hypoventilation on Cochlear Blood Flow and Endocochlear Direct-Current Potential

Yamamoto

Makimoto

Kawakami

et al. 1995

ORL

View full text Add to dashboard Cite

To understand the importance of oxygen transport to the inner ear tissue, we studied, in guinea pigs, the relationship between cochlear blood flow and endocochlear direct-current potential (EP) under different respiratory conditions. EP, a functional parameter of the stria vascularis, was recorded by a microelectrode inserted into the lateral wall of the chochlea. To measure the cochlear blood flow (CoBF), we employed laser Doppler flowmetry and recorded the flow with a probe placed on the same spot on the lateral wall. During 3 min of asphyxia, CoBF and systemic blood pressure showed irregular biphasic increases, while the EP decreased to reach a negative value. In the hypoxemia experiment, which was induced by stepwise reduction of the respiratory rate to 60%, increases in CoBF and blood pressure were evident during hypoventilation with an intermediate position of EP in the positive range. The mechanisms of these increases in two parameters are discussed from the viewpoints of sympathicotonic activity in the autonomic nervous system and the vasodilating action of CO₂ during hypercapnia. In the hyperoxemia experiment, which was induced by stepwise increase in the respiratory rate to 140%, CoBF and blood pressure were found to decrease during hyperventilation with no significant change of EP. The decrease in blood pressure was considered to be due to the increase in intrathoracic pressure caused by the increased rate of artificial respiration. As for the concomitant decrease in CoBF, chemical regulation of PCO₂ in the vascular bed of the lateral wall of the cochlea was thought to be a contributory factor.

show abstract

Relationship between cochlear blood flow and perilymphatic oxygen tension

Cited by 9 publications

References 13 publications

Effects of Neuropeptide Y on Cochlear Blood Flow in Guinea Pigs

Effects of Neuropeptide Y on Cochlear Blood Flow in Guinea Pigs

Studies of inner ear blood flow in animals and human beings

Effects of Hyperventilation and Hypoventilation on Cochlear Blood Flow and Endocochlear Direct-Current Potential

Contact Info

Product

Resources

About