Naoyuki Kanoh

Prenatal maturation of endocochlear potential and electrolyte composition of inner ear fluids in guinea pigs

SummaryThe maturation of the endocochlear potential (EP) and the inner ear fluid ionic composition were studied in fetal and neonate guinea pigs. The concentration of sodium and potassium in endolymph and perilymph approximated adult values more than 2 weeks before birth. Endolymph had acquired its specific ionic composition before the onset of cochlear microphonics (52–55 gestation days, results of other authors). Positive EP was recorded starting on day 62 of gestation. The EP rose fast to reach near adult level at birth. It is speculated that the negative EP recorded after the onset of cochlear microphonics was an artifact, probably a result of fetal hypoxia. The significance of the negative EP recorded before the onset of the cochlear microphonics is discussed in relation to the source of the anoxic negative EP in the adult animal.

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.

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.

Effect of Glycerol on the Ep Decrease Caused by Furosemide

A change in endocochlear potential (EP) following furosemide injection was observed in regard to prior glycerol administration in two groups of guinea pigs. In one group, various doses of furosemide (20, 30, 40, 50 mg/kg) were injected, while in the other, glycerol (50 v/v %, 1 ml/kg) was injected prior to the furosemide (20, 30, 40 mg/kg) injection. In the glycerol-furosemide group, the decrease in EP was 40% greater than in the furosemide group. Therefore, glycerol was thought to potentiate the EP lowering action of furosemide. Such an effect of glycerol was assumed to be resulted by facilitating the access of furosemide to the site of action in the stria vascularis.

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

ZusammenfassungBlutserum, Liquor cerebrospinalis und Perilymphe von Scala vestibuli und Scala tympani wurden von 85 normalen Meerschweinchen vor und nach i.v. Glycerolapplikation entnommen und die Na- und K-Konzentration bestimmt. Dabei wurde nach Glycerolgabe ein deutlicher Anstieg der Na-Konzentration in der Perilymphe der Scala tympani und im Liquor festgestellt, während die Perilymphe der Scala vestibuli keine Veränderungen zeigte. Die Zunahme der Na-Konzentration wird auf die Dehydration durch das Glycerol zurückgeführt, wobei die unterschiedliche Reaktion beider Perilymphen noch weiterer Untersuchungen bedarf. Die erhobenen Befunde könnten zur Aufklärung der Glycerolwirkung auf das Hören beim endolymphatischen Hydrops von Bedeutung sein.SummarySerum, 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.

The Effect of Furosemide on Sodium and Potassium Concentrations in Guinea-pig Perilymph

SummaryTo 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.

Observations on immunologic parameters in laryngeal cancer patients

SummaryPatients with laryngeal cancer were examined immunologically before treatment and for 1–10 years after treatment. In the pretreatment group, the percentage of T cells, lymphocyte blastoid reaction (PHA, concanavalin A), and skin reactions (PHA) were generally in the normal range, but absolute numbers of T cells and lymphocytes were reduced in most patients. In the group with no recurrence after surgery, the absolute number of T cells and lymphocytes, IgG · FcR+T cells (Tγ), and skin reactions was normal in many cases. The group with recurrence showed reduced percentage of T cells and an absolute number of T cells and lymphocytes. The absolute number of T cells and lymphocytes and the PPD skin reaction increased after surgery in some cases, but reductions in some of the parameters were noted in a few cases long after surgery. Radiation therapy for patients with tumors at early stages did not significantly change the percentage of T cells or the skin reactions.

Effect of Glycerol on Furosemide-caused EP Decrease in Guinea Pig Neonates

Furosemide, a loop diuretic, reduces the endocochlear potential in guinea pigs. In our previous experiment using adult guinea pigs, glycerol was thought to open the blood-cochlea barrier and to help furosemide to reach its site of action in the stria vascularis. The present study was designed to determine whether or not the same potentiation by glycerol occurs in neonate guinea pigs. In one group, furosemide (10-30 mg/kg) was administered, while in another group, 50 v/v% glycerol (1 ml/kg) was administered 15 minutes prior to the injection of furosemide. Furosemide reduced the EP significantly more in neonates than in adults. This effect was not potentiated in the glycerol-pretreated group. From these findings, it seemed conceivable that the neonate blood-cochlea barrier still remains immature in some functions.

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 Menieres disease, oral administration of glycerol is more effective than intravenous injection.

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.