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Provoked flux motion of cochlear blood flow measured with laser Doppler flowmetry in guinea pig.
Acta Otolaryngol. 1993 Sep; 113(5):609-14.AO

Abstract

Although progress has been made in the study of cochlear blood flow (CBF) regulation since laser Doppler flowmetry (LDF) was introduced, cochlear vasomotion has not been investigated. Therefore, the primary objective of this study was to determine if oscillatory fluctuations of CBF could be provoked. Guinea pigs were anesthetized with diazepam (5 mg/kg) and fentanyl (0.32 mg/kg). Blood pressure (BP) was recorded from a carotid artery cannula. The cochlea and pons cerebellum were ventrally exposed; the bilateral CBF and brain blood flow (BBF) or skin blood flow (SBF) were monitored by LDF. After administration of phentolamine (0.25-0.75 mg/kg, i.v.), ipsilateral CBF in 7 of 16 animals showed a 2-5 min episode of oscillation. During artificial hyperventilation, continuous oscillation of CBF was recorded (the flux motion frequency was 3.5 +/- 0.5 cycles per min and its amplitude 25.8 +/- 5.6% from baseline). The time-dependent flux change (the waveform) was the same throughout a single cochlea but different between cochleae of the same animal. Compared to BBF, CBF vasomotion frequency was lower, and amplitude larger. SBF exhibited no such motion. Flux motion could be eliminated by inhalation of pure oxygen or 5% CO2 in oxygen or by the smooth muscle relaxants, papaverine and hydralazine. Phentolamine-induced vasomotion may be due to a hypotensive perfusion pressure, and hyperventilation-enhanced vasomotion may be caused by changing blood gas concentrations and by hormonal or neuronal activity. Oxygen and CO2 inhalation slightly increased BP and this change in perfusion pressure was probably associated with weakened vasomotion.(

ABSTRACT

TRUNCATED AT 250 WORDS)

Authors+Show Affiliations

Kresge Hearing Research Institute, University of Michigan, Ann Arbor.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8266787

Citation

Ren, T Y., et al. "Provoked Flux Motion of Cochlear Blood Flow Measured With Laser Doppler Flowmetry in Guinea Pig." Acta Oto-laryngologica, vol. 113, no. 5, 1993, pp. 609-14.
Ren TY, Nuttall AL, Miller JM. Provoked flux motion of cochlear blood flow measured with laser Doppler flowmetry in guinea pig. Acta Otolaryngol. 1993;113(5):609-14.
Ren, T. Y., Nuttall, A. L., & Miller, J. M. (1993). Provoked flux motion of cochlear blood flow measured with laser Doppler flowmetry in guinea pig. Acta Oto-laryngologica, 113(5), 609-14.
Ren TY, Nuttall AL, Miller JM. Provoked Flux Motion of Cochlear Blood Flow Measured With Laser Doppler Flowmetry in Guinea Pig. Acta Otolaryngol. 1993;113(5):609-14. PubMed PMID: 8266787.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Provoked flux motion of cochlear blood flow measured with laser Doppler flowmetry in guinea pig. AU - Ren,T Y, AU - Nuttall,A L, AU - Miller,J M, PY - 1993/9/1/pubmed PY - 1993/9/1/medline PY - 1993/9/1/entrez SP - 609 EP - 14 JF - Acta oto-laryngologica JO - Acta Otolaryngol VL - 113 IS - 5 N2 - Although progress has been made in the study of cochlear blood flow (CBF) regulation since laser Doppler flowmetry (LDF) was introduced, cochlear vasomotion has not been investigated. Therefore, the primary objective of this study was to determine if oscillatory fluctuations of CBF could be provoked. Guinea pigs were anesthetized with diazepam (5 mg/kg) and fentanyl (0.32 mg/kg). Blood pressure (BP) was recorded from a carotid artery cannula. The cochlea and pons cerebellum were ventrally exposed; the bilateral CBF and brain blood flow (BBF) or skin blood flow (SBF) were monitored by LDF. After administration of phentolamine (0.25-0.75 mg/kg, i.v.), ipsilateral CBF in 7 of 16 animals showed a 2-5 min episode of oscillation. During artificial hyperventilation, continuous oscillation of CBF was recorded (the flux motion frequency was 3.5 +/- 0.5 cycles per min and its amplitude 25.8 +/- 5.6% from baseline). The time-dependent flux change (the waveform) was the same throughout a single cochlea but different between cochleae of the same animal. Compared to BBF, CBF vasomotion frequency was lower, and amplitude larger. SBF exhibited no such motion. Flux motion could be eliminated by inhalation of pure oxygen or 5% CO2 in oxygen or by the smooth muscle relaxants, papaverine and hydralazine. Phentolamine-induced vasomotion may be due to a hypotensive perfusion pressure, and hyperventilation-enhanced vasomotion may be caused by changing blood gas concentrations and by hormonal or neuronal activity. Oxygen and CO2 inhalation slightly increased BP and this change in perfusion pressure was probably associated with weakened vasomotion.(ABSTRACT TRUNCATED AT 250 WORDS) SN - 0001-6489 UR - https://www.unboundmedicine.com/medline/citation/8266787/Provoked_flux_motion_of_cochlear_blood_flow_measured_with_laser_Doppler_flowmetry_in_guinea_pig_ L2 - https://www.tandfonline.com/doi/full/10.3109/00016489309135872 DB - PRIME DP - Unbound Medicine ER -