Perilymph Of Scala Tympani Research Articles

Na and nonelectrolyte entry into inner ear fluids of the rat.

Kinetics of hydrophilic solute entry into endolymph (EL), perilymph (PL), and cerebrospinal fluid (CSF) were studied after intravenous administration (sodium, urea, glycerol, mannitol, sucrose) and cerebral lateral ventricle injection (urea, sucrose) of tracers in anesthetized rats. Samples of cochlear EL, PL of scala vestibuli (PLV), PL of scala tympani (PLT), and cisternal CSF were obtained. The data showed slow entry of tracers in PLV, PLT, and CSF as follows: Na greater than urea greater than mannitol approximately sucrose; slower entry of mannitol and sucrose in PLT and CSF than in PLV; 1 h delayed peak of radioactivity in PLV compared with the immediate peaks in PLT and CSF after CSF injection, and the value of PLV peak was 13% that in CSF; extremely slow entry of nonelectrolytes in EL. These results indicate that PLV originates mainly from plasma across a blood-perilymph barrier that restricts the entry of small hydrophilic solutes. The blood-perilymph barrier is most likely composed of an endothelial barrier associated with an epithelial secretion. The latter could be located at the vasculo-epithelial zone of the spiral limbus.

Vasopressin entry into the inner ear fluids of the rat.

The entry of arginine-vasopressin (AVP) and sucrose into cochlear endolymph, perilymph of scala vestibuli (PLV), perilymph of scala tympani (PLT), and cisternal cerebrospinal fluid (CSF) was studied, in anesthetized rats, after the administration into the cerebral lateral ventricle of a 10 microliter solution containing the radioactive tracers. Both tracers were detected in PLV, PLT, and CSF but not in endolymph. Monoexponential decay curves were calculated for PLV, PLT, and CSF, and for each tracer no difference was found between the regression lines calculated for the different fluids. These results indicate that (i) injection into the cerebral lateral ventricle is a useful tool to study the permeability of the cochlear epithelium to different solutes and (ii) no specific transport system exists for AVP across the cochlear epithelium, suggesting that AVP may exert its effect via the perilymphatic side of the stria vascularis.

Modifications of cochlear microphonic frequency responses following transient changes of hydrostatic pressure in the perilymph.

Cochlear microphonic potential was recorded with differential electrodes implanted in the various turns of the guinea-pig cochlea. Isointensity frequency responses were plotted in normal conditions and after excessive displacements of the cochlear partition. These displacements were provoked by changes of hydrostatic pressure in the perilymph of scala tympani or scala vestibuli. Typical modifications of the frequency response were observed. The most noticeable was a division in two parts of the response zone which suggested the existence of two resonance peaks. Scanning electron microscopy revealed that changes of hydrostatic pressure provoked alterations of the stereocilia in the outer rows of external hair cells, probably in relation with a decoupling of the tectorial membrane from the organ of Corti. These results are discussed in terms of possible alterations of cochlear micromechanics.

Effect of Peroral Glycerol Administration on Inner Ear Fluid Electrolytes of Guinea Pigs

After the oral administration of 50% glycerol (12 mL/kg), serum, CSF and inner ear fluids from scala tympani perilymph, scala vestibuli perilymph, and scala media endolymph were collected from normal guinea pigs under sodium pentobarbital anesthesia (25–35 mg/kg). The sodium and potassium concentrations were determined by microflame photometry. Increases in sodium concentrations were found in CSF, scala tympani perilymph, scala vestibuli perilymph, and cochlear endolymph. No significant change was observed in the serum. These sodium increases were considered to be due to the dehydration caused by the osmotic action of glycerol. Potassium concentration was increased only in scala tympani perilymph. Oral administration of glycerol was found to be more gradual and effective in dehydration compared to intravenous injection.

Effects of intravenous glycerol injection on inner ear fluid electrolytes.

Under sodium pentrobarbital anesthesia (20-30 mg/kg, i.p.), normal guinea pigs received an intravenous injection of glycerol (1.0 ml/kg). Serum, cerebrospinal fluids (CSF) and inner ear fluids were collected from the scala tympani perilymph, scala vestibuli perilymph and the scala media endolymph. The sodium and potassium concentrations were assessed using microflame photometry. Increases in sodium concentration were found in the CSF and the scala tympani perilymph; no significant changes were observed in the serum, scala vestibuli perilymph or the scala media endolymph. These sodium increases were considered to be a result of the dehydration process caused by the osmotic agent glycerol. Increases in potassium concentration were found only in the scala vestibuli perilymph.

The effect of furosemide on sodium and potassium concentrations in guinea-pig perilymph.

To observe the effects of furosemide on electrolyte concentrations in inner-ear fluids, experiments were performed on 286 normal guinea-pigs. Intravenous injection of furosemide (15 mg/kg) induced increases of Na concentration in scala tympani perilymph, scala vestibuli perilymph, and cerebrospinal fluid (CSF). K concentrations in both perilymphs and CSF were also increased by furosemide. The increased Na concentrations are thought to be due to the dehydration of body fluids induced by the diuretic action of furosemide. The increase of K concentrations in perilymphs could be attributable to either a characteristic action of furosemide on the electrolyte transport in the inner ear or a secondary change caused by a rise of K concentration in the endolymph.

Effects of Glycerol on the Inner Ear Fluid Electrolytes of Guinea Pigs —Oral and Intravenous Administration—

Under sodium pentobarbital anesthesia (25-35 mg/kg), serum, CSF and inner ear fluids from scala tympani perilymph, scala vestibuli perilymph, and scala media endolymph were collected from normal guinea pigs after the oral administration of glycerol (50%, 12 ml/kg) or the intravenous injection of glycerol (1.0 ml/kg). The sodium and potassium concentrations were assessed by microflame photometry. The electrolyte dynamics of the inner ear fluids were compared after these two routes of administration. Serum: There was no significant change in Na or K levels after either route of administration. CSF: The Na concentration increased rapidly after both intravenous and oral administrations of glycerol and remained high until the end of the experiment. The K concentration did not change significantly after intravenous injection. Scala tympani perilymph: The Na concentration increased transiently, after intravenous glycerol, while after oral administration it increased slowly and steadily. The K concentration increased only after oral administration. Scala vestibuli perilymph: The Na level increased slowly and steadily only after oral administration of glycerol, and the K level increased slightly after intravenous injection. Scala media endolymph: No changes in the K level occurred after either route of administration. After oral administration the Na level increased. These experiments show that dehydration persists longer after oral than after intravenous administration of glycerol. In the diagnosis of Meniere's disease, oral administration of glycerol is more effective than intravenous injection.

Effects of reserpinization on the electrolytes distribution in inner ear fluids of guinea pig.

Reserpine (2 mg/kg and 10 mg/kg, i.p.), an adrenergic blocker, was administered to normal guinea pigs, and samples of serum, CSF, scala tympani perilymph, scala vestibuli perilymph and cochlear endolymph were collected. The concentrations of Na and K in these fluids were then assessed to observe electrolyte distributions. Both Na and K concentrations were reduced in serum. In CSF, the Na concentration was markedly depressed, while the K concentration remained unchanged. Scala tympani perilymph showed a pattern of electrolyte changes similar to that in CSF. In scala vestibuli perilymph, the Na concentration was unaltered, but the K concentration was lowered. Cochlear endolymph exhibited no change of the Na concentration but there was a marked decrease in the K concentration. These changes are thought to be attributable to the indirect blockage of energy producing systems in membrane transport in the inner ear by the reserpine-induced depletion of catecholamines.

The Effects of Glycerol on the Electrolyte Concentration of Guinea Pig Perilymph

Serum, cerebrospinal fluid (CSF), and inner ear fluids from scala tympani perilymph and scala vestibuli perilymph were collected from normal, anesthetized guinea pigs (Sodium pentobarbital 20-30mg/kg, I. P.) which received both intravenous glycerol injection (1.0ml/kg) and peroral glycerol administration (50W/V%, 12ml/kg). The sodium and potassium concentrations were assessed using microflame photometry.The following results were obtained.1) Serum: There was no significant difference between the two administrations in electrolyte dynamics.2) CSF: With both administrations the sodium concentration was found to be increased rapidly and maintained at high levels until the end of our experiments. The electrolyte dynamics were different with respect to the potassium concentration. It did not change with intravenous administration but with peroral administration it increased slightly.3) Scala Tympani Perilymph: The sodium concentration was increased with both administrations but the type of increasing curve was different. With intravenous injection the curve was transient, while with peroral administration it was a gradual up-slope curve. No change was observed with intravenous administration with respect to the potassium concentration, while with peroral administration an up-slope curve was seen.4) Scala Vestibuli Perilymph: The sodium concentration did not change with intrvenous administration, but it changed with peroral administration. An increase in the potassium concentration was produced with intravenous administration but not with peroral administration.In conclusion, when we use the glycerol test in detecting endolymphatic hydrops, peroral administration of glycerol has been found to be more effective than intravenous glycerol injection. Dehydration occurs most severely 2-3 hours after peroral administration, and the time course resembles the clinical glycerol test.

K, Cl, and H2O entry in endolymph, perilymph, and cerebrospinal fluid of the rat.

The kinetics of radioactive potassium, chloride, and water entry into endolymph, perilymph, and cerebrospinal fluid were studied after intravenous administration of tracers in anesthetized and nephrectomized rats. Samples of cochlear endolymph, perilymph of scala vestibuli, perilymph of scala tympani, and cisternal cerebrospinal fluid were obtained. The data showed: 1) a rapid turnover of water in endolymph, perilymph, and cerebrospinal fluid, since 3H2O equilibrated with plasma in a few minutes; 2) a slow entry of 42K and 36Cl in perilymph, since 36Cl equilibrated with plasma after 2 h and 42K did not at 6 h; 3) an extremely slow entry of 42K and 36Cl in endolymph, since no equilibrium with plasma was obtained within the 5 h of the experiments. The comparison of the compartmental analysis of our data with the results of other studies using perilymphatic perfusion of tracers indicated that perilymph rather than plasma may be considered as the precursor of endolymph.

Amino acid profiles in inner ear fluids and cerebrospinal fluid.

The levels of 19 amino acids in utricular endolymph, vestibular and cochlear perilymph, and cerebrospinal fluid of guinea pigs were determined using gradient elution reverse phase high performance liquid chromatography of the o-phthaldialdehyde-ethanethiol adducts with fluorescence detection. Aspartate and glutamate were significantly higher in endolymph than in perilymph, in agreement with earlier results on cochlear fluids based on enzymatic fluorometric techniques. All other amino acids tested were significantly lower in the endolymph, in most cases by an order of magnitude. Vestibular perilymph and perilymph of scala vestibuli are virtually identical. Amino acid levels were all higher in perilymph of scala vestibuli than in cerebrospinal fluid; two by an order of magnitude. All differences were statistically significant, with the exception of aspartate. Amino acid levels in perilymph of scala tympani were highly variable dependent upon sampling technique, and no definite values are therefore presented. Comparisons with results from other laboratories, technical pitfalls, and possible implications and interpretations of the results are presented.

Specificity of action of vanadate to the organ of corti.

Although vanadate strongly inhibits Na/K-ATPase activity of the stria vascularis in vitro, it initially causes no depression of the ouabain-sensitive endocochlear potential (EP) when perfused perilymphatically or via the vasculature. However, when the perilymph of scala tympani is replaced with artificial media containing 0.1 to 1 mM vanadate, there is a large (about 17 mV) increase in the EP of the second cochlear turn. Further experiments showed that the cochlear microphonics declined during the time in which the EP increased, and that the response of these two potentials to vanadate is greater in the second turn than in the first. Injection of 50 n1 of 1 mM vanadate (in artificial endolymph) into the endolymphatic space of the second turn caused no increase in the EP. These results support the notion that the early effects of vanadate are on the contra-luminal membranes of cells of the organ of Corti rather than on the stria vascularis. By superimposing anoxia or furosemide (i.v.) upon vanadate intoxication, we determined that the initial increase of the compound EP due to vanadate alone was due to a reduction in magnitude of the negative component of the EP. It is argued that of the three prevalent theories concerning the generation of the negative EP, the data tend to support the hypothesis that the intracellular potential of the hair cells gives rise to the negative EP.

Effects of glycerol on sodium and potassium concentrations in guinea pig perilymph.

Serum, cerebrospinal fluid (CSF), scala vestibuli perilymph, and scala tympani perilymph were collected from 85 normal guinea pigs both before and after i.v. administration of glycerol (1 ml/kg), and the sodium and potassium concentrations were assessed using a microflame photometer. Marked increases in sodium concentrations were observed in scala tympani perilymph and CSF, while there was a slight decrease in the serum and there was no significant change in scala vestibuli perilymph. These increases in sodium concentrations are considered to occur in the dehydration process in the body fluids mentioned above. On the other hand, increase in the potassium concentrations was found only in scala vestibuli perilymph and thus cannot be explained by simple dehydration process. This potassium elevation in scala vestibuli perilymph should be understood by further experiment on endolymph. It became evident that scala vestibuli perilymph differs from scala tympani perilymph and CSF in the dynamics of electrolytes after glycerol administration. In this regard, the nature of the scala vestibuli as fluid space should be studied in future. The above findings obtained in the present study may imply the significance in elucidating the glycerol effect on hearing of endolymphatic hydrops case.

生理的食塩水静注の外リンパ電解質濃度におよぼす影響

Serum, cerebrospinal fluid (CSF), scala vestibuli perilymph and scala tympani perilymph were collected from 104 normal anesthetized guinea pigs (Sodium Pentobarbital 20-30mg/kg I. P.) both before and after intravenous administration of normal saline (1.5ml/kg), and the sodium and potassium concentrations were assessed using a microflame photometer.Increase in the sodium concentration was observed in scala vestibuli perilymph, while there was no significant change in scala tympani perilymph, CSF and serum.The potassium concentration did not significantly change in perilymph, CSF and serum.The results of the present study indicate that a relatively small amount of injected normal saline affects the concentration of electrolytes in scala vestibuli perilymph. Thus, each perilymphatic space seems to have its own characteristic system in electrolyte transport.

Endolymphatic and intracellular resting potential in the alligator lizard cochlea.

Endolymphatic potential (EP) and intracellular resting potentials (RPs) in the cochlea of the alligator lizard were measured with micropipets. The EP (defined as the dc electric potential recorded between the endolymph in scala media and the perilymph in scala tympani or scala vestibuli) had a mean value of +16 mV (in 96 ears). The RPs (defined as the dc potentials recorded between the intracellular and perilymphatic spaces) were different in the distal portion of the cochlear nerve (range to -56 mV, mean of -23 mV in 158 cells) from those in the region of the basilar papilla (range to -154 mV, mean of -73 mV in 623 cells). In identified cells in the region of the basilar papilla, the mean values of RPs of hyaline epithelial cells (-113 mV in 7 cells) and supporting cells (-93 mV in 13 cells) were more negative than of hair cells (-73 mV in 5 cells). Differences in measured RPs could reflect differences in the resting potentials of these cells and/or their source resistances. RPs measured in the basilar papilla of the alligator lizard are compared with those obtained in other vertebrate hair cell organs.

Chemical composition in various compartments of inner ear fluid

Sodium, potassium, chloride, glucose and total protein were determined in samples of scala vestibuli perilymph, scala tympani perilymph, CSF, cochlear endolymph and utricular endolymph from normal cats. Small but significant differences were evident in the concentrations of sodium and potassium between the scala vestibuli and scala tympani perilymph. It was also apparent that each compartment of endolymph has different values for sodium and potassium concentrations. Compared with the endolymph, the perilymph was found to contain a higher concentration of glucose and total protein. These findings are discussed from the view point of biological significance.

Tight and gap junctions in a vertebrate inner ear.

The auditory organ of the alligator lizard has been investigated with the transmission electron microscope using methods which distinguish between tight and gap junctions. There is a continuous zone of tight junctions located near the endolymphatic surface of the organ forming a boundary between the endolymph in scala media and the interstitial spaces between the cells. No such tight junctions were observed between the perilymph of scala tympani and the interstitial fluid within the organ. Small gap junctions occur between hair cells and supporting cells and large gap junctions occur between adjacent supporting cells. The locations of the tight junctions suggest that the composition of the intercellular fluid in the receptor organ is probably more like perilymph than like endolymph. The presence of gap junctions between hair cells and supporting cells provides a possible morphological basis for the occurrence of intracellular responses to sound in supporting cells, and for elctric coupling of receptor cells.

Proteinstudie Zur Frage Der Perilymphsubstitution Durch Liquor Cerebrospinalis Via Aquaeductus Cochleae.

Total protein contents in the perilymphy of Scala vestibuli and Scala tympani as well as in the cerobrospinal fluid (CSF) of guinea-pigs were determined, by which specimens were taken under the following various conditions: With or without subarachnoidal puncture before perilymph collection, by varying the amount of perilymph taken from Scala tympani, by fractionating collection and under post mortem condition. The results suggest that under physiological conditions the CSF also flows through the cochleae aqueduct and the protein concentration in the Scala tympani decreases especially in the basal winding. Because the protein content in CSF is inaverage four times lower than in fluids of the inner ear it is of preference to consider the question of connection between the CSF and the fluids of the inner ear. In the specimens taken the blood contamination was estimated on the basisof erythrocytes in the connection capillaries under microscope. The protein content in the perilymph of Scala vestibuli was found significantly higher in relation to perilymph of Scala tympani.

Symposium: new data for noise standards. II. Effects of insulin on glucose concentrations in inner ear fluids and cochlear microphonics.

AbstractFluids from various inner ear compartments were taken from 77 ears of 70 normal, healthy cats and were analyzed for glucose concentration by the microchemical technique employing the hexokinase method. Perilymph of the scala vestibuli, perilymph of the scala tympani and C.S.F. had almost identical concentrations of glucose with the values approximately 80 mg/100 ml. Glucose concentrations of each fluid showed the significant relationship with serum glucose level except that of utricular and cochlear endolymph. Utricular endolymph glucose level was found to be lower (41.9 mg/100 ml) than the above three fluids and higher than cochlear endolymph (11.2 mg/100 ml). The significant difference of glucose concentration found between cochlear and utricular endolymph in the present study is further support for the independent nature of each endolymphatic compartment.Sodium, potassium and glucose were analyzed in serum, C.S.F. and inner ear fluids up to five hours after intravenous regular insulin (30 units/kg). Sodium, potassium and glucose concentrations were unchanged in both cochlear and utricular endolymph during hypoglycemia. In contrast glucose concentrations in C.S.F., scala tympani perilymph, and scala vestibuli perilymph began to decrease at 90 minutes after regular insulin infusion and fell to their lowest levels in the period during 180 to 300 minutes after the infusion. A significant decrease of potassium concentration was found first in serum and later in the C.S.F., scala vestibuli, and scala tympani perilymph. For five hours after insulin infusion there is no significant change in cochlear microphonics during hypoglycemia (20 mg percent).

Perilymph displacement by cerebrospinal fluid in the cochlea.

On histological examination, the cochlear aqueduct of guinea pigs has a large open lumen, unlike the tissue-filled periotic duct of primates. Hence, the guinea pig's large patent periotic duct appears capable of accommodating a bulk flow of cerebrospinal fluid from the subarachnoid space into the scala tympani if an egress for this fluid was provided by experimentally perforating the cochlea. In order to measure this flow the cochlea in anesthetized guinea pigs was surgically exposed and a single opening was drilled in the basal turn of the scala tympani. All of the displaced perilymph was collected in a calibrated, silicone-coated micropipette sealed into this hole, and; was measured directly by recording the advance of the meniscus in the micropipette. The displacement rates were typically 0.8 to 1 μliter/min, but could be temporarily increased by short periods of respiratory depression and changes in body orientation. From a consideration of anatomical and hydrodynamic relationships, it is concluded that a major source of the fluid which displaces perilymph in the opened guinea pig cochlea is cerebrospinal fluid which enters the scala tympani via the cochlear aqueduct. These results indicate that if a single opening is made into the cochlea at the apex, all of the perilymph in scala tympani (8.0 utters) would be displaced in approximately 10 min. Furthermore, these results have important implications for the technique of intracochlear injection used to study the effects of ions and drugs on the cochlea, because the continuous displacement of perilymph from the opened cochlea consequently removes the test substance previously injected into the scala tympani.