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A study of the electrochemistry and osmotic relationships of the cochlear fluids in the neonatal rat at the time of the development of the endocochlear potential.
J Physiol. 1971 Feb; 212(3):739-61.JP

Abstract

1. Changes in the endocochlear potential between the 8th and 18th days after birth were investigated in the rat. Initially the potential was low but its magnitude increased rapidly between the 11th and 16th day. During the 13th and 14th days the rate of increase was approximately 1 mV/hr.2. The rapid potential increase arose virtually simultaneously in all three turns of the cochlea.3. Histological examination revealed the cochlea, including the hair cells of Corti's organ and the stria vascularis, to be fully mature before the period of rapid change in the endocochlear potential, apart from the cells of Claudius, whose final development coincided with the latter part of this phase.4. The endolymphatic sodium concentration (average 1.0 m-equiv/l.) had attained the very low adult level in the earliest period studied. The potassium and chloride concentrations were slightly below the normal adult levels, the result of some degree of general hypo-osmolality present at this time.5. The endolymphatic ionic concentrations remained unchanged during the phase of rapid increase in the endocochlear potential.6. The findings thus indicate that the distinctive endolymphatic ionic composition and the endocochlear potential arise largely independently and in succession during cochlear maturation.7. No differences in osmotic pressure were demonstrated between endolymph, perilymph and serum. The problems concerning the homoeostasis of the inner ear fluids do not consequently seem to be complicated by unusual hydrodynamic aspects.8. Alterations in body fluid osmolality, produced by intraperitoneal injection of water or hypertonic glycerol, were accompanied by simultaneous changes in the osmotic pressures of the inner ear fluids. Some portion of the membranes bounding the endolymphatic space is therefore considered to be freely permeable to water.9. The investigations provide no further information about the nature of the endocochlear potential, although an increase in the electrical resistance of the cochlear duct membranes is thought responsible for its appearance. The time relationships of this period support the concept that the potential is an essential feature of the mechano-electric transduction process.

Authors

No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

5557069

Citation

Bosher, S K., and R L. Warren. "A Study of the Electrochemistry and Osmotic Relationships of the Cochlear Fluids in the Neonatal Rat at the Time of the Development of the Endocochlear Potential." The Journal of Physiology, vol. 212, no. 3, 1971, pp. 739-61.
Bosher SK, Warren RL. A study of the electrochemistry and osmotic relationships of the cochlear fluids in the neonatal rat at the time of the development of the endocochlear potential. J Physiol (Lond). 1971;212(3):739-61.
Bosher, S. K., & Warren, R. L. (1971). A study of the electrochemistry and osmotic relationships of the cochlear fluids in the neonatal rat at the time of the development of the endocochlear potential. The Journal of Physiology, 212(3), 739-61.
Bosher SK, Warren RL. A Study of the Electrochemistry and Osmotic Relationships of the Cochlear Fluids in the Neonatal Rat at the Time of the Development of the Endocochlear Potential. J Physiol (Lond). 1971;212(3):739-61. PubMed PMID: 5557069.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A study of the electrochemistry and osmotic relationships of the cochlear fluids in the neonatal rat at the time of the development of the endocochlear potential. AU - Bosher,S K, AU - Warren,R L, PY - 1971/2/1/pubmed PY - 1971/2/1/medline PY - 1971/2/1/entrez SP - 739 EP - 61 JF - The Journal of physiology JO - J. Physiol. (Lond.) VL - 212 IS - 3 N2 - 1. Changes in the endocochlear potential between the 8th and 18th days after birth were investigated in the rat. Initially the potential was low but its magnitude increased rapidly between the 11th and 16th day. During the 13th and 14th days the rate of increase was approximately 1 mV/hr.2. The rapid potential increase arose virtually simultaneously in all three turns of the cochlea.3. Histological examination revealed the cochlea, including the hair cells of Corti's organ and the stria vascularis, to be fully mature before the period of rapid change in the endocochlear potential, apart from the cells of Claudius, whose final development coincided with the latter part of this phase.4. The endolymphatic sodium concentration (average 1.0 m-equiv/l.) had attained the very low adult level in the earliest period studied. The potassium and chloride concentrations were slightly below the normal adult levels, the result of some degree of general hypo-osmolality present at this time.5. The endolymphatic ionic concentrations remained unchanged during the phase of rapid increase in the endocochlear potential.6. The findings thus indicate that the distinctive endolymphatic ionic composition and the endocochlear potential arise largely independently and in succession during cochlear maturation.7. No differences in osmotic pressure were demonstrated between endolymph, perilymph and serum. The problems concerning the homoeostasis of the inner ear fluids do not consequently seem to be complicated by unusual hydrodynamic aspects.8. Alterations in body fluid osmolality, produced by intraperitoneal injection of water or hypertonic glycerol, were accompanied by simultaneous changes in the osmotic pressures of the inner ear fluids. Some portion of the membranes bounding the endolymphatic space is therefore considered to be freely permeable to water.9. The investigations provide no further information about the nature of the endocochlear potential, although an increase in the electrical resistance of the cochlear duct membranes is thought responsible for its appearance. The time relationships of this period support the concept that the potential is an essential feature of the mechano-electric transduction process. SN - 0022-3751 UR - https://www.unboundmedicine.com/medline/citation/5557069/A_study_of_the_electrochemistry_and_osmotic_relationships_of_the_cochlear_fluids_in_the_neonatal_rat_at_the_time_of_the_development_of_the_endocochlear_potential_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0022-3751&date=1971&volume=212&spage=739 DB - PRIME DP - Unbound Medicine ER -