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In vivo measurements of Na+ and K+ in cochlear endolymph of the guinea pig
Vol . 9, Part II, pp. 183-188, 1970. Life Sciences Printed in Gr~.t Britain
Pergamon Press
IN VIVO MEASUREMENTS OF Na + AND K+ IN COCHLEAR ENDOLYMPH OF THE GUINEA PIG* Fumiro Suga, Teunehiko Nakashima and James B. Snow, Jr . Department of Otarhinolaryngology, University of Oklahoma Medical Center Oklahoma City, Oklahoma
(Received il July 1989; in final form 13 November 1989) Introduction
In 1957, Eisenuran et al characterized the ranges of glass composition which had high sensitivities for Na + and K+ .1,2
Rinks constructed Na + and K+
glass micscelectrodes to measure the intracellular cation activitiea . 2~ 3,4 Bekesy reported in 1952 that cochlear endolymph of the guinea pig had a positive resting potential in reference to perilymph .5~6
In 1954, Smith et al
using a flame photometer reported that the endolymph of the guinea pig had a high potassium and low sodium concentration and perilymph had a low potassium and high sodium concentration.?
There has been no in vivo measurement of
cation activities in the inner ear. It has been well known that living cells have a high potassium and low sodium concentration and have a negative resting potential .
There has been
no explanation of the positive resting potential of cachlear endolymph in spite of its high potassium and low sodium concentration .
The present
investigation was undertaken to measure in vivo the sodium and potassium ion activities in the endolymph of the cochlea. Method The sodium indicator micrcelectrode was made of Corning NAS 11-18 glass capillary tubing, and the potassium indicator microelectrode was made of Corning NAS 27-4 glass capillary tubing .
The tubing was pulled to a micro-
*Supported in part by the National Institute of Neurologie Diseases and Stroke Grants NB 05180-05 and NB 05418-06 . 183
164
Na+ ,AND K+ IN COCHLEAR ENDOLYMPH
pipette with an electrode pulley . closed by heating.
The tip opening of the micropipette was
The micrcelectrode was filled with ether, and air bubbles
were removed from the electrode . absolute alcohol.
Vol . 9, No . 3
Ether in the electrode was replaced by
The sodium indicatar electrode was finally filled with
0 .1 molar sodium chlaride solution, and the potassium indicator electrode was filled with 0 .1 molar potassium chlaride solution . adjusted to pH 7 .6 by use of Tris-buffer.
These solutions were
The electrode was coated by
insulation materials except at the tip and was connected to a silver-silver chlaride wire .
The tip diameter of the electrode was smaller than 50 microns .
In measuring the Na + activity, the reference electrode was a micropipette filled with 1 .5 molar rubidium chloride solution and was connected to a eilves~silver chlaride wire .
The NAS 11-18 glass micrcelectrode was used as
the reference electrode in measuring the K+ activity because the NAS 27-4 glass electrode has a sensitivity far Na+ as well as for K+ .
The sensitiviTy
of Na + and K+ indicator micrcelectrodes was calibrated in sodium and potassium solutions of various concentrations .
The potential difference between the
indicator electrode and the reference electrode was recarded with Beckman's Zeromatic II electrometer and a Type R Dynograph . Nineteen guinea pigs were used in this study . anaesthetized with pentobarbital sodium .
The animals were
A tracheostomy was perfarmed, and
the pulmonary ventilation was maintained by a respirator . exposed through the auditory bulla. preserved . turn .
The cochlea was
The tympanic membrane and ossicles were
The small holes were made in the scaly media of the basal cochlear
Both cation indicator and reference microelectrodes were placed in the
scaly media with the use of an operating microscope and micromanipulators . The endolymphatic resting potential was recarded from the RbCl micrcelectrode with a high impedance amplifier to determine the site of the ehctrodc . Changes in Na + and K+ activities were continuously recw-ded ~:ith the pen recorder .
Vol. 9, No. 3
Na+ AND K+ IN COCHLEAR TNDOLYMPH
185
Observations The cation sensitivity of the glass electrodes was
Preliminary Teats :
studied in sodium chloride solutions and potassium chloride solutions of various concentrations . sensitivity for Na +.
The NAS 11-18 glass electrode had a selective
The NAS 27-4 glass indicatar electrode with the caramel
reference electrode showed a higher sensitivity far K+ than far Na+ but showed a relatively high sensitivity far Na +.
The recording from the
NAS 27-4 glass indicator electrode and the NAS 11-18 glass reference electrode showed a selective sensitivity for K+ .
The potential difference between the
indicatar electrode and the reference electrode was proportional to the cation ion concentration .
SEC.
No~Yidoala-Cda~l nhr~
K CI
Naq
~i
K~Ydoalorv-hb~nlw~
FIG .
1
The responses of the blasa electrodes in three combinations far changes in the Na and K+ concentrations . In Vivo Measurements :
Na + and K+ activities in cochlear endolymph were
stable in the resting condition.
Intense sound stimulation to the ear in-
creased Na + activity and decreased K+ activity in cochlear endolymph.
188
Na+ AND K+ IN COCHLEAR ENDOLYMPH .
3EC . 3PL
Vol. 9, No . 3
Na+ 1n ENDOL.YMPH 2000 cps tone (`-l
120
FIG. 2 Changes in Na+ acrivity in cochlear endolymph due to 2,000 Nz tone ati.~li . The Na+ activity increased due to tone arimulation of high intensities . The threshold to change the endolymphatic Na+ and
K+
activities was
approximately 100 dB sound pressure level for 2,000 Nz tones.
The Na + and
K+ activities retaaned to the cattrol level after the sound atimularion. This pheiwmenon was reproducible . The eadolympharic Na } acrivity increased during asphyxia which was produced by tracheal cannula occulsion, while the endolymphatic decreased during asphyxia .
K+
activity
Na + AND K+ IN COCHLEAR ENDOLYbIPH
Vol. 9, No. 3
187
FIG . 8 Changes in endolymphatic Na+ activity due to asphyxia . The Na + activity gradually increased during asphyxia and returned rapidly to the control level after pulmonary re-ventilation. A rebound was seen in the recovery .
o
I
>:
a
a
a
e~
~
s
e
o
x ~
K' In ENOOLYMPN
FIG . 4 Changes in endolymphatic K+ activity due to asphyxia . The K+ activity decreased dining asphyxia and returned to the control level after re-ventilation . An overshoot was seen in the recovery . They began to change approximately one half minute after the onset of asphyxia and returned toward normal rapidly following re-ventilation .
A
rebound ar decrease was often observed in the endolymphatic Na+ activity after re-ventilation, and a rebound ar increase was often observed in the endolymphatic K+ activity after re-ventilation . Discussion The increase in Na + activity and the decrease in K+ activity in the cochlear endolymph during intense sound stimulation may be duc to an in-
188
Na+ AND K + IN COCHLEAR ENDOLYMPH
Vol . 9, No. 3
creased permeability of Reissner's membrane and the basilar membrane which divide the endolymph from the perilymph since it occurs immediately with acoustic stimulation .
The threshold of endolymphatic Na + and K+ activity
changes for acoustic stimuli is approximately the same as that of the temporary decrease in the cochlear microphonica . 8 The increase in Na+ activity and the decrease in K+ activity in the endolymph during asphyxia may be due to a decrease in the potassium pump action of the endolymphatic system . The endolymphatic DC potential decreases during intense sound stimulatfon . 8
It also decreases during asphyxia and often shows an overshoot in
recovery .9
The K+ activity of the cochlear endolymph appears proportional
to the endolymphatic DC potential,
and the Na + activity appears to be
irneraely proportional to the DC potential . Acknowledgement The authors wish to express our thanks to Mrs . J .L . Green for her assistance . 800 Nartheast 13th Street Oklahoma City, Oklahoma References 1.
Eisenman, G ., Rudin, D .O . and Casby, J. U. :
2.
Eisenman, G . :
Science 126,
831 (1957) .
Glass Electrodes for Hydrogen and Other Cations .
M. Dekker, Inc ., New York, 1967 . 3.
Hinke, J .A .M . : .
Nature 184, 1257, (1959) .
4.
Hinke, J .A .H . :
J. Physiol. 156,
5.
Bekesy, G .Von :
J . Acouet . Soc . Amer . 24, 72 (1952) .
6.
Suga, F., Marimiteu, T . and Matauo, K . :
7.
Smith, C .A ., Lowry, O .H . and Wu, M.L . :
B.
Suga, F. :
9.
Marimitsu, T., Mateuo, K . artel Suga, F . :
3I4 (1961) .
Ann. Otol . 73, 924 (1964) . Laryngoscope 64, 141 (1954) .
Otologia F~kuoka 8, Suppl. 3, 187 (1962) . Ann. Otol . 74, 22 (1965) .
Pergamon Press
IN VIVO MEASUREMENTS OF Na + AND K+ IN COCHLEAR ENDOLYMPH OF THE GUINEA PIG* Fumiro Suga, Teunehiko Nakashima and James B. Snow, Jr . Department of Otarhinolaryngology, University of Oklahoma Medical Center Oklahoma City, Oklahoma
(Received il July 1989; in final form 13 November 1989) Introduction
In 1957, Eisenuran et al characterized the ranges of glass composition which had high sensitivities for Na + and K+ .1,2
Rinks constructed Na + and K+
glass micscelectrodes to measure the intracellular cation activitiea . 2~ 3,4 Bekesy reported in 1952 that cochlear endolymph of the guinea pig had a positive resting potential in reference to perilymph .5~6
In 1954, Smith et al
using a flame photometer reported that the endolymph of the guinea pig had a high potassium and low sodium concentration and perilymph had a low potassium and high sodium concentration.?
There has been no in vivo measurement of
cation activities in the inner ear. It has been well known that living cells have a high potassium and low sodium concentration and have a negative resting potential .
There has been
no explanation of the positive resting potential of cachlear endolymph in spite of its high potassium and low sodium concentration .
The present
investigation was undertaken to measure in vivo the sodium and potassium ion activities in the endolymph of the cochlea. Method The sodium indicator micrcelectrode was made of Corning NAS 11-18 glass capillary tubing, and the potassium indicator microelectrode was made of Corning NAS 27-4 glass capillary tubing .
The tubing was pulled to a micro-
*Supported in part by the National Institute of Neurologie Diseases and Stroke Grants NB 05180-05 and NB 05418-06 . 183
164
Na+ ,AND K+ IN COCHLEAR ENDOLYMPH
pipette with an electrode pulley . closed by heating.
The tip opening of the micropipette was
The micrcelectrode was filled with ether, and air bubbles
were removed from the electrode . absolute alcohol.
Vol . 9, No . 3
Ether in the electrode was replaced by
The sodium indicatar electrode was finally filled with
0 .1 molar sodium chlaride solution, and the potassium indicator electrode was filled with 0 .1 molar potassium chlaride solution . adjusted to pH 7 .6 by use of Tris-buffer.
These solutions were
The electrode was coated by
insulation materials except at the tip and was connected to a silver-silver chlaride wire .
The tip diameter of the electrode was smaller than 50 microns .
In measuring the Na + activity, the reference electrode was a micropipette filled with 1 .5 molar rubidium chloride solution and was connected to a eilves~silver chlaride wire .
The NAS 11-18 glass micrcelectrode was used as
the reference electrode in measuring the K+ activity because the NAS 27-4 glass electrode has a sensitivity far Na+ as well as for K+ .
The sensitiviTy
of Na + and K+ indicator micrcelectrodes was calibrated in sodium and potassium solutions of various concentrations .
The potential difference between the
indicator electrode and the reference electrode was recarded with Beckman's Zeromatic II electrometer and a Type R Dynograph . Nineteen guinea pigs were used in this study . anaesthetized with pentobarbital sodium .
The animals were
A tracheostomy was perfarmed, and
the pulmonary ventilation was maintained by a respirator . exposed through the auditory bulla. preserved . turn .
The cochlea was
The tympanic membrane and ossicles were
The small holes were made in the scaly media of the basal cochlear
Both cation indicator and reference microelectrodes were placed in the
scaly media with the use of an operating microscope and micromanipulators . The endolymphatic resting potential was recarded from the RbCl micrcelectrode with a high impedance amplifier to determine the site of the ehctrodc . Changes in Na + and K+ activities were continuously recw-ded ~:ith the pen recorder .
Vol. 9, No. 3
Na+ AND K+ IN COCHLEAR TNDOLYMPH
185
Observations The cation sensitivity of the glass electrodes was
Preliminary Teats :
studied in sodium chloride solutions and potassium chloride solutions of various concentrations . sensitivity for Na +.
The NAS 11-18 glass electrode had a selective
The NAS 27-4 glass indicatar electrode with the caramel
reference electrode showed a higher sensitivity far K+ than far Na+ but showed a relatively high sensitivity far Na +.
The recording from the
NAS 27-4 glass indicator electrode and the NAS 11-18 glass reference electrode showed a selective sensitivity for K+ .
The potential difference between the
indicatar electrode and the reference electrode was proportional to the cation ion concentration .
SEC.
No~Yidoala-Cda~l nhr~
K CI
Naq
~i
K~Ydoalorv-hb~nlw~
FIG .
1
The responses of the blasa electrodes in three combinations far changes in the Na and K+ concentrations . In Vivo Measurements :
Na + and K+ activities in cochlear endolymph were
stable in the resting condition.
Intense sound stimulation to the ear in-
creased Na + activity and decreased K+ activity in cochlear endolymph.
188
Na+ AND K+ IN COCHLEAR ENDOLYMPH .
3EC . 3PL
Vol. 9, No . 3
Na+ 1n ENDOL.YMPH 2000 cps tone (`-l
120
FIG. 2 Changes in Na+ acrivity in cochlear endolymph due to 2,000 Nz tone ati.~li . The Na+ activity increased due to tone arimulation of high intensities . The threshold to change the endolymphatic Na+ and
K+
activities was
approximately 100 dB sound pressure level for 2,000 Nz tones.
The Na + and
K+ activities retaaned to the cattrol level after the sound atimularion. This pheiwmenon was reproducible . The eadolympharic Na } acrivity increased during asphyxia which was produced by tracheal cannula occulsion, while the endolymphatic decreased during asphyxia .
K+
activity
Na + AND K+ IN COCHLEAR ENDOLYbIPH
Vol. 9, No. 3
187
FIG . 8 Changes in endolymphatic Na+ activity due to asphyxia . The Na + activity gradually increased during asphyxia and returned rapidly to the control level after pulmonary re-ventilation. A rebound was seen in the recovery .
o
I
>:
a
a
a
e~
~
s
e
o
x ~
K' In ENOOLYMPN
FIG . 4 Changes in endolymphatic K+ activity due to asphyxia . The K+ activity decreased dining asphyxia and returned to the control level after re-ventilation . An overshoot was seen in the recovery . They began to change approximately one half minute after the onset of asphyxia and returned toward normal rapidly following re-ventilation .
A
rebound ar decrease was often observed in the endolymphatic Na+ activity after re-ventilation, and a rebound ar increase was often observed in the endolymphatic K+ activity after re-ventilation . Discussion The increase in Na + activity and the decrease in K+ activity in the cochlear endolymph during intense sound stimulation may be duc to an in-
188
Na+ AND K + IN COCHLEAR ENDOLYMPH
Vol . 9, No. 3
creased permeability of Reissner's membrane and the basilar membrane which divide the endolymph from the perilymph since it occurs immediately with acoustic stimulation .
The threshold of endolymphatic Na + and K+ activity
changes for acoustic stimuli is approximately the same as that of the temporary decrease in the cochlear microphonica . 8 The increase in Na+ activity and the decrease in K+ activity in the endolymph during asphyxia may be due to a decrease in the potassium pump action of the endolymphatic system . The endolymphatic DC potential decreases during intense sound stimulatfon . 8
It also decreases during asphyxia and often shows an overshoot in
recovery .9
The K+ activity of the cochlear endolymph appears proportional
to the endolymphatic DC potential,
and the Na + activity appears to be
irneraely proportional to the DC potential . Acknowledgement The authors wish to express our thanks to Mrs . J .L . Green for her assistance . 800 Nartheast 13th Street Oklahoma City, Oklahoma References 1.
Eisenman, G ., Rudin, D .O . and Casby, J. U. :
2.
Eisenman, G . :
Science 126,
831 (1957) .
Glass Electrodes for Hydrogen and Other Cations .
M. Dekker, Inc ., New York, 1967 . 3.
Hinke, J .A .M . : .
Nature 184, 1257, (1959) .
4.
Hinke, J .A .H . :
J. Physiol. 156,
5.
Bekesy, G .Von :
J . Acouet . Soc . Amer . 24, 72 (1952) .
6.
Suga, F., Marimiteu, T . and Matauo, K . :
7.
Smith, C .A ., Lowry, O .H . and Wu, M.L . :
B.
Suga, F. :
9.
Marimitsu, T., Mateuo, K . artel Suga, F . :
3I4 (1961) .
Ann. Otol . 73, 924 (1964) . Laryngoscope 64, 141 (1954) .
Otologia F~kuoka 8, Suppl. 3, 187 (1962) . Ann. Otol . 74, 22 (1965) .