PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Labyrinthine Fluids”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1984

Pars superioris in endolymphatic hydrops.

A volumetric study was made of the endolymphatic compartments of the pars superioris (utricle and semicircular canals). Selected for this comparative study were 15 ears from subjects with unilateral endolymphatic hydrops, 15 contralateral ears, and 15 normal ears. There was an increase in the total volume as well as in the utricular volume. This increase was also correlated with vestibular and auditory symptoms, disclosing a substantial increase in volumes with increasing hearing loss. The magnitude of volume increase correlated inversely with the frequency of vertiginous attacks; no correlation was found with the duration of the disease.

Aged↗
PubMed1988

Volume flow rate of perilymph in the guinea-pig cochlea.

The rate of longitudinal flow of perilymph has been measured using an ionic tracer technique. Spread of the tracer trimethylphenylammonium (TMPA) along the perilymphatic scalae was monitored with ion-selective microelectrodes following injection of a minute bolus (approximately 50 nl) of 150 mM TMPAC1 one turn away. This amount of TMPA had virtually no toxic effect on cochlear function. The spread of tracer by longitudinal volume flow and passive diffusion were separated by comparing tracer movements in both apical and basal directions along the scalae in two groups of animals. Experimental findings were compared with a mathematical model which combined diffusion and volume flow. Our results demonstrated that when electrodes were completely sealed into the cochlea, the rate of longitudinal volume flow in scala tympani was extremely slow, approximately 1.6 nl/min in the apical direction. Longitudinal flow was not detectable in scala vestibuli. When the otic capsule was perforated, flow rates of over 1 microliter/min were recorded in scala tympani, probably as a result of cerebrospinal fluid entry through the cochlear aqueduct. When the cochlea was sealed (with recording electrodes in place) and cerebrospinal fluid pressure was released, there was no significant basally-directed flow of perilymph in scala tympani. These findings support the concept that perilymph composition is maintained by local, cochlear mechanisms which do not involve longitudinal volume flow. They provide strong evidence that perilymph is not secreted in one region and resorbed at a spatially distant site.

Action Potentials↗
PubMedDate not supplied

Nature of blood-labyrinth barrier in experimental conditions.

The blood-labyrinth barrier is concept that has evolved based on marked difference in chemical composition between perilymph and blood. Studies reported here have been designed to manipulate physiologic, metabolic, and pharmacologic conditions in experimental animals in order to determine the characteristics of this regulatory mechanisms. Tracer studies of uptake of sodium, calcium, and albumin from blood into perilymph showed that these substances penetrate into inner ear fluids quite slowly. Injections of ototoxic substances (kanamycin, furosemide) show limited transport of these agents into perilymph. Administration of an osmotic agent (urea) resulted in a parallel but delayed elevation of perilymph concentration. The possible role of a alteration of blood-labyrinth barrier in inner ear disorders has been discussed.

Animals↗
PubMedDate not supplied

Perilymph production and cochlear blood flow.

In rodents at least, the main sources of the perilymph fluid are (1) influx of CSF through the cochlear aqueduct, and (2) blood flow dependent local production within the cochlea. Experimental data are presented that give a ratio of 22:78 percent for those sources. The perilymph production thus derives mainly from the cochlear blood flow. It is concluded that measurements of the perilymph production can be used as indirect measurements of the inner ear blood flow under various experimental conditions. Two experimental examples are referred to.

Acidosis, Respiratory↗
PubMedDate not supplied

Cerebrospinal fluid absorption in the rabbit. Inner ear pathways.

Fifteen adult rabbits were perfused intrathecally with horseradish peroxidase (HRP) for 20-30 min under conditions that prevented any increase in cerebrospinal fluid (CSF) pressure. Histologic and ultrastructural examination of the cochlea disclosed HRP deposits along the cochlear and vestibular branches of the auditory nerve and beyond their ganglia, in a) epineural and perineural spaces; b) intraneural spaces reaching the membrane of myelinated axons via nodes of Ranvier; and c) extending beyond the epineurium into area lymphatics. HRP was also found in the basilar membrane, along with deposits in the scalae tympani, vestibuli, media and the spiral ligament. The endolymph also received HRP which followed vestibular nerve fibers and penetrated between sustentacular and hair cells of the cristae ampullaris and both maculae. HRP permeated interendothelial spaces lining the modiolus to reach the scala vestibuli lymphatics close to all the above areas were also permeated by HRP, but the inner tunnel was devoid of the marker.

Absorption↗
PubMed1979

[Blockage of cochlear aqueduct for examination of perilymph (guinea pig) (author's transl)].

To prevent the perilymph (guinea pig) from contamination with CSF during the sampling the aqueductus cochleae (AC) was blocked by injection of tissue adhesive into the meningeal aperture. The control of an exact blockage of AC was carriedout by examination of perilymph-outflow after opening the cochlea (injection of fluorescein-Na into the CSF-space), analysis of perilymph-protein-concentration, macroscopic and microscopic examination of the temporal bones. In all cochleae we have found the same morphological structures, notwithstanding whether the AC was blocked (for a time from 30 min to 7 weeks) or not: The cochlear aqueduct is filled with a mesh of mesenchymal tissue, which grows more dense towards the cochlear aperture andcontinues into the round window membrane. From scala tympani the AC is always limited by one layer of cells forming a sort of membrane (under light microscope). It seems possible that CSF moves in the inner of the round window membrane between AC and subepithelian space of middle ear mucosa, whereas perilymph of scala tympani is not in direct contact with the flow of CSF. The scala tympanic side of the round window membrane may be a big area for diffusion and there also may be an exchange between CSF and perilymph. The outflow of CSF into the cochlea after experimental opening of the cochlea is an artifact, caused by damage of pressure equilibration between CSF-space and cochlea. 30 min and 5--7 weeks after blockage no morphologicaland electrophysiological alterations from those of the control ears were to be seen. The protein concentration, however, increased significantly 5--7 weeks after blockage from normally about 200 mg/100 ml toalmost the double especially in the scala tympani (see Table 1).

Action Potentials↗