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PubMedDate not supplied

[Electrophoretic examination of protein distribution in guinea pig perilymph].

Perilymph and serum of guinea pigs were investigated using immunoelectrophoresis and polyacrylamide gel electrophoresis. The molecular weights of the perilymph proteins were estimated by electrophoresis in a linear polyacrylamide gel gradient (3-20%). The immunoelectropherograms and the polyacrylamide gel electropherograms of equivalent amounts of perilymph protein and serum protein are nearly the same. The immunological detection of the perilymph proteins indicates that they are serum proteins. The clear identification of the individual proteins fails because of missing monospecific antisera against the individual proteins of guinea pig. High-molecular proteins (range of the molecular weight estimation 67 000-290 000) are also detectable in the perilymph according to the molecular weight estimation.

Animals↗
PubMedDate not supplied

Secretory otitis media. Comparison of nasal and aural cytology.

Aural and nasal cytology is compared in a series of 105 patients with secretory otitis media (SOM). In aural smears the cellular picture consisted mainly of lymphocytes, leukocytes and phagocytes but eosinophils and basophilic cells were absent. In the nose, the most frequent cells were leukocytes, while lymphocytes were seldom seen in greater numbers. Increased numbers of eosinophils were found in 20% of the patients. IgE values in the serum of 69 patients and in 8 aural effusions were mostly within normal limits and SOM could not be considered to be a result of circulating IgE-dependent reaction. Cytotoxic leukocyte test with food allergens to test this etiologic factor in SOM is at present in progress.

Adolescent↗
PubMedDate not supplied

Measurement of oxygen tension in human perilymph.

The oxygen tension of the human perilymph has been determined without complications by using a technique based upon the polarographic principle. Carbon dioxide produced the most marked increase in oxygen tension in the human perilymph. No change in the perilymphatic PO2 was observed after administration of eupaverine and low molecular weight dextran. 5% CO2-95%O2 has been found to be the gas mixture producing the largest increase in oxygen tension in the human perilymph, without side effects. In order to achieve maximal oxygenation of the perilymph, the therapeutic administration of 5% CO2-95% O2 should continue for at least 30 minutes. At this preliminary stage it is not possible to assess the accuracy of the presented technique in determining the presence of a vascular disorder of the inner ear in patients.

Blood Pressure↗
PubMedDate not supplied

The influence of perilymphatic pressure on the displacement of the tympanic membrane. A quantitative study on human temporal bones.

A model study on human temporal bones was performed. A microflow method was used in order to assess the possibility of making indirect recordings of changes in the inner ear pressures. Changes in the perilymphatic pressure were recorded as displacements of the tympanic membrane, the stapedius reflex being artificially elicited by forces applied briefly to the stapedius tendon. Changes in the perilymphatic pressures in the range of +/-15 cm H2O affected the position of the tympanic membrane and the "stapedius reflex response". The microflow method used seems suitable for the clinical recording of changes in the intralabyrinthine pressure.

Adult↗
PubMedDate not supplied

Labyrinthine input to the vestibular nuclei of the awake cat.

The labyrinthine input to the vestibular nuclei was investigated in 24 awake cats. Stimulus consisted of electrical shocks given through bipolar silver wire electrodes, implanted in the utricular and lateral ampullar nerves. Throughout the vestibular nuclei, single units were recorded extracellularly with glass micropipettes filled with Fast Green. The tracts of the penetrating electrodes were identified histologically. In all four nuclei units responding to both labyrinths outnumbered unilaterally responding neurones with certain differences between the individual nuclei. Excitatory as well as inhibitory responses were observed, polysynaptic being more common than mono- or disynaptic ones. No monosynaptic contralateral responses were seen. The latency distribution of contralateral responses closely mirrored that of ipsilateral responses within each nucleus. Both excitatory and inhibitory responses fell into relatively segregated populations, based upon latency distribution. This implies separate pathways for labyrinthine input to the vestibular nuclei.

Animals↗
PubMedDate not supplied

Volume displacement of the tympanic membrane at stapedius reflex activity in different postures. Studies on variations in perilymphatic pressure.

With the microflow method the volume displacement of the tympanic membrane and its direction of movement can be recorded at stapedius reflex contraction. There is an outward or inward movement of the tympanic membrane, which is affected by changes in posture. The results indicate that the perilymphatic pressure in man varies with the posture and that these variations can be measured indirectly outside the tympanic membrane. This can only be done, however, on condition that there are no pressure variations across the tympanic membrane. This method opens up new ways of studying possible pressure changes in the inner ear in acute diseases.

Auditory Threshold↗
PubMedDate not supplied

Ionic composition of the endolymph and sensory transduction in labyrinthine organs.

The role of various ions in stimuli conversion has been investigated in isolated frog semicircular canals, by replacing the endolymph with solutions deprived in turn of Na+, K+, Cl- and Ca++. Mechanical and electrical stimuli were employed and slow ampullar and nerve potentials were recorded, together with the afferent discharge of impulses in the eighth nerve. The results support evidence that K+ is the carrier of the receptor current, as postulated in Davis' hypothesis, while Ca++ is essential in the processes which allow the current to be modulated during cupula deflections and therefore endon hair cells with mechanical sensitivity.

Acoustic Stimulation↗
PubMed1979

Elimination kinetics of furosemide in perilymph and serum of the chinchilla. Neuropharmacologic correlates.

This study was done to determine the comparative elimination kinetics of furosemide from chinchilla perilymph and serum, and to correlate perilymph concentration with changes in endocochlear potential. The elimination kinetics of furosemide (FU) were determined in sera and perilymph obtained from chinchillas injected with 100 mg/kg i.v. of FU. Concentrations of FU exhibited a linear decay pattern in serum and perilymph over the initial 60 minutes. The rate of decline of furosemide levels in perilymph was about four times slower than the rate of fall in serum. Chronic treatment (25 mg/kg i.p. every 12 hours) did not appear to influence the level of drug at 60 minutes after a dose of FU (100 mg/kg IV). Chinchillas were also studied following doses of FU ranging from 25--200 mg/kg i.v. to see the effect on endocochlear potential (EP). A positive correlation was found between FU dosage, the maximum millivolt reduction of EP and the time to initiation of recovery of EP. The perilymph concentration of furosemide when the EP began to recover was 5 microgram/ml (1.5 x 10(-5) M). Knowledge of furosemide kinetics may ultimately be applied to prevent ototoxicity in patients.

Animals↗
PubMedDate not supplied

Obliteration of the ductus reuniens.

The ductus reuniens was successfully obliterated in 52 guinea pig ears. Histopathological study showed that a majority of these specimens demonstrated cochlear hydrops, saccular collapse and normal utricle. These results support the theory of longitudinal flow of endolymph from the cochlea toward the endolymphatic sac via the ductus reuniens and saccule. A major source of endolymph in the saccule appears to be the scala media. In another set of 11 animals in which the ductus reuniens was first obstructed and two months later the endolymphatic duct was blocked, endolymphatic hydrops was shown in the cochleae, saccules, and utricles of all but one. The evidence suggests that cochlear hydrops was caused by obliteration of the ductus reuniens, and the saccular and utricular hydrops occurred subsequently as the result of blockage of the endolymphatic duct. Remnants of otolithic membrane which were attached to the distended saccular wall indicate that the membrane which had collapsed onto the macula after obliteration of the ductus reuniens is capable of subsequent distension. This experiment supports the concept of endolymph flow from the utricle and canals toward the endolymphatic sac. A blocked cutus reuniens might also explain the pathophysiological basis for the auditory form of Meniere's disease.

Animals↗
PubMedDate not supplied

The nature of the ototoxic actions of ethacrynic acid upon the mammalian endolymph system. I. Functional aspects.

The endolymphatic changes produced by an intravenous injection of 60 mg kg-1 ethacrynic acid were followed for up to 120 min using conventional and ion-sensitive (Na+, K+ and pH) microelectrodes in the rat. They were found to be caused by three distinct effects upon the endolymph system. Initially, the drug completely inhibited the strial potential-producing and cation-transporting processes. Recovery began quickly and was rapid at first. Then its rate declined considerably, probably due to diminution in strial energy production of delayed onset and prolonged duration. Coincident with these actions upon active transport, there was a decrease in the overall cation permeability of the endolymph system. This followed a different time course and affected K+ much more than Na+. The findings also provided further information about the mechanisms responsible for the normal endolymphatic composition. Qualitatively similar results were obtained in a subsidiary study on guinea pigs.

Animals↗
PubMedDate not supplied

The effects of inhibition of the strial Na+-K+-activated ATPase by perilymphatic ouabain in the guinea pig.

The endolymphatic effects of perilymphatic ouabain (2 X 10(-3) M) were followed in 3 guinea pigs using ion-sensitive micro-electrodes, enabling a Na+-related permeability increase to be identified. Investigation of the strial ultrastructural changes in 11 more animals revealed early swelling of the marginal cells, while the intermediate and basal cells became shrunken with characteristically dark-staining cytoplasm. The subsequent cellular alterations were complex. The findings suggest that a major function of the Na+-K+-activated ATPase is preservation of the normal intracellular environment, inhibition resulting in widespread indirect effects. General measures of strial function, consequently, do not document just ATPase inhibition.

Animals↗
PubMedDate not supplied

A survey of the effects of loop diuretics on the zonulae occludentes of the perilymph-endolymph barrier by freeze fracture.

The acute (30 min) effects of the loop diuretics piretanide, ethacrynic acid, bumetanide, furosemide, and azosemide, and the chronic (8 days) effects of furosemide and bumetanide on the zonulae occludentes (tight junctions) of the perilymph-endolymph barrier in the stria vascularis and in Reissner's membrane of the basal cochlear turns were studied by freeze-fracture. Quantitative analysis of their effects indicated that the structural integrity of the barrier was modified by either as increase or a decrease in the number, depth, and density of the strands of the tight junctions of the strial marginal cells. Only azosemide appeared to modify the tight junctions between the epithelial cells of Reissner's membrane, but it had little effect on the strial junctions. The tight junctions between the basal cells of the stria appeared to be the least affected by the various loop diuretics, although piretanide appeared to increase randomly the intercellular spaces lying between the strands.

Animals↗
PubMedDate not supplied

Effects of exposure to noise on permeability to potassium of the endolymph-perilymph barrier in guinea pigs.

Healthy guinea pigs were exposed to broadband noise at 115 dBA for 7 days. When perfusion of the scala vestibuli was carried with artificial perilymph containing 43K, the 43K concentrations in the perilymph of the scala tympani were very low in both control and noise-exposed guinea pigs. The transport rate constant for K+ was computed by utilizing compartmental analysis. The results indicate that exposure to noise at 115 dBA for 7 days does not alter the permeability to K+ of Reissner's membrane or the lateral wall of the cochlear duct but does decrease K+ conductance of the organ of Corti.

Action Potentials↗
PubMed1982

Electrophoretic separation and identification of perilymph proteins in cases of acoustic neuroma.

Previous studies of perilymph proteins have emphasised the difficulty of obtaining samples free of blood or serum proteins. The present investigation has established a method of polyacrylamide gel electrophoresis, which enables contaminated specimens to be readily identified and therefore discarded. Analysis of uncontaminated samples has confirmed the presence of an elevated perilymph protein in cases of acoustic neurinomata. Perilymph proteins have been separated and identified and although no characteristic pattern of proteins associated with acoustic neurinomata has emerged, further work should be undertaken to establish the site of origin of perilymph proteins and the pattern of abnormalities to be expected in pathological processes.

Electrophoresis, Polyacrylamide Gel↗
PubMed1982

Semicircular canals: measurement of endolymphatic and cupular displacements at threshold.

The left horizontal semicircular canal of the leopard frog (Rana pipiens) was exposed and the entire intact nerve was draped over a platinum-iridium hook for recording action potentials (a.p.'s). The preparation was then rotated sinusoidally in the horizontal plane at 0.3 Hz with varying angular displacements. The arm of the canal was then transected, and a fine micropipette ligated in place in one end of the arm. Artificial endolymph was pumped into and out of the canal at the same frequency, while the amplitude of the displacement was varied from sub-threshold to supra-threshold values as determined from the resulting a.p. train. By comparing the two a.p. trains, it was determined that the movement of endolymph in the canals was 5.3 x 10(-8) cm3/deg/s, and that the threshold displacement of the midpoint of the cupula was 7.6 x 10(-5) cm (0.76 micrometers).

Action Potentials↗
PubMedDate not supplied

The site of initial production and transport of effusion materials in otitis media serosa. A study on rat middle ear cavity.

The aim of this experimental study was to localize the site of the initial production of effusion in the middle ear cavity. Via the tympanic bulla the passage between the lateral attic compartment and the rest of the middle ear (isthmus tympanicus) was blocked with Gelfoam and/or the Eustachian tube likewise with a polyethylene tube in both normal and sympathectomized rats. Effusion was thus produced in the attic, while concomitantly dilated vessels were seen in the pars flaccida, which after a couple of days gradually withdrew in a medial direction to form a retraction pocket. Sympathectomy did not prevent the production of effusion. The stream of effusion was nasal to the promontorium and the tensor tympani muscle. Its transport seems to be influenced by the ventilation through the tympanic tube.

Animals↗
PubMed1984

Pathogenesis of Meniere's disease and Meniere's syndrome.

Meniere's disease can only be studied in patients, since it does not occur spontaneously in animals nor can it be induced in them. However, aspects of the disease such as endolymphatic hydrops can be usefully studied in animals. A study of the natural history (epidemiology) of Meniere's disease demonstrated the three major symptoms (triad) to be vestibular symptoms, auditory symptoms, and aural pressure. Bilaterality occurs in at least one out of 3 patients, and may approach 50% over full lifespans. Aural pressure (74.1%) was common, as was positional vertigo (85.9%) during and/or between attacks. Clinical variants such as vestibular Meniere's disease could persist for 25 years or more. Understanding the pathogenesis of Meniere's requires a study of known and unknown causes. In this study, Meniere's disease (cause unknown) was differentiated from Meniere's syndrome (cause known). Meniere's disease or syndrome can occur years after some inciting cause; thus all forms of Meniere's can be considered to have a delayed onset. Meniere's syndrome can occur as a sequel to syphilis, otosclerosis, infection (for example otitis media), or trauma. Endolymphatic hydrops explained on the basis of quantity and quality of endolymph is found in all forms of Meniere's disease and syndrome. Representative cases and pathological examples are discussed. Hydrops of the pars inferior (cochlear duct and saccule) is the most important finding in Meniere's disease. In some (but not most) cases, ruptures of the membranes are seen. The saccule can distend into the lateral semicircular canal. Symptomatic attacks are explained on the basis of both physical and biochemical phenomena. This study discusses concepts of pathogenesis of the disease, finding both theories of longitudinal (slow) and radial (fast) flow to be operational. Longitudinal flow, however, appears to be more important than radial flow, especially in advanced Meniere's where perilymph in the scala vestibuli and vestibule disappears and is replaced by membranous labyrinth. Meniere's disease (idiopathic) and Meniere's syndrome (cause known) probably occur as a result of endolymphatic absorptive dysfunction (the site being endolymphatic duct and sac). Hypocellularity of the mastoid and periaqueductal air cells, hypodevelopment of Trautmann's triangle, and anterior displacement of the lateral sinus are likely to be important findings associated with developmentally dysfunctional absorption of endolymph.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗