In vitro electrophysiology of developing genioglossal motoneurons in the rat

P. A. Nunez-Abades, J. M. Spielmann, G. Barrionuevo, William Cameron

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

1. Experiments were performed to determine the change in membrane properties of genioglossal (GG) motoneurons during development. Intracellular recordings were made in 127 GG motoneurons from rats postnatal ages 1-30 days. 2. The input resistance (R(in)) and the membrane time constant (τ(m)) decreased between 5-6 and 13-15 days from 84.8 ± 25.4 (SD) to 47.0 ± 18.9 MΩ (P <0.01) and from 10.0 ± 4.2 to 7.3 ± 3.3 ms (P <0.05), respectively. During this period, the rheobase (I(rh)) increased (P <0.01) from 0.13 ± 0.07 to 0.27 ± 0.14 nA, and the percentage of cells exhibiting inward rectification increased from 5 to 40%. Voltage threshold (V(thr)) of the action potential remained unchanged postnatally. 3. There was also a postnatal change in the shape of the action potential. Specifically, between 1-2 and 5-6 days, there was a decrease (P <0.05) in the spike half-width from 2.23 ± 0.53 to 1.45 ± 0.44 ms, resulting, in part, from a steepening (P <0.05) of the slope of the falling phase of the action potential from 21.6 ± 10.1 to 32.9 ± 13.1 mV/ms. The slope of the rising phase also increased significantly (P <0.01) between 1-2 and 13-15 days from 68.4 ± 31.0 to 91.4 ± 44.3 mV/ms. 4. The average duration of the medium afterhyperpolarization (mAHP(dur)) decreased (P <0.05) between 1-2 (193 ± 53 ms) and 5-6 days (159 ± 43 ms). Whereas the mAHP(dur) was found to be independent of membrane potential, there was a linear relationship between the membrane potential and the amplitude of the medium AHP (mAHP(amp)). From this latter relationship, a reversal potential for the mAHP(amp) was extrapolated to be -87 mV. No evidence for the existence of a slow AHP was found in these developing motoneurons. 5. All cells analyzed (n = 74) displayed adaptation during the first three spikes. The subsequent firing pattern was classified into two groups, adapting and nonadapting. Cells at birth were all adapting, whereas all cells but two from animals 13 days and older were nonadapting. At the intermediate age (5-6 days), the minority (27%) was adapting and the majority (73%) was nonadapting. 6. The mean slope of primary range for the first interspike interval (1st ISI) was ~90 Hz/nA. This value was similar for both adapting and nonadapting cells and did not change postnatally. However, there was a significantly lower (P <0.01) frequency of the mean ISI for adapting (27.7 ± 8.2 Hz/nA) than for nonadapting cells (36.5 ± 11.6 Hz/nA). During development, there was a trend to increase the maximum firing frequency achieved during sustained current injection. Newborn (1-2 days) motoneurons had a maximal frequency of 25.5 ± 10.1 Hz, whereas motoneurons at 19-30 days fired at 42.2 ± 19.7 Hz. 7. The mean ISI of GG motoneurons exhibited only a single linear frequency-current (f-I) relationship, whereas the 1st ISI in some cells exhibited both a primary and a secondary range. The occurrence of cells having a secondary range of the 1st ISI increased postnatally. 8. We hypothesize that there is a specific developmental sequence for the membrane properties of GG motoneurons in which channels shaping the action potential and afterpotential mature earlier than those channels governing its passive membrane properties.

Original languageEnglish (US)
Pages (from-to)1401-1411
Number of pages11
JournalJournal of Neurophysiology
Volume70
Issue number4
StatePublished - 1993
Externally publishedYes

Fingerprint

Electrophysiology
Motor Neurons
Action Potentials
Membranes
Membrane Potentials
In Vitro Techniques
Parturition
Injections

ASJC Scopus subject areas

  • Physiology
  • Neuroscience(all)

Cite this

Nunez-Abades, P. A., Spielmann, J. M., Barrionuevo, G., & Cameron, W. (1993). In vitro electrophysiology of developing genioglossal motoneurons in the rat. Journal of Neurophysiology, 70(4), 1401-1411.

In vitro electrophysiology of developing genioglossal motoneurons in the rat. / Nunez-Abades, P. A.; Spielmann, J. M.; Barrionuevo, G.; Cameron, William.

In: Journal of Neurophysiology, Vol. 70, No. 4, 1993, p. 1401-1411.

Research output: Contribution to journalArticle

Nunez-Abades, PA, Spielmann, JM, Barrionuevo, G & Cameron, W 1993, 'In vitro electrophysiology of developing genioglossal motoneurons in the rat', Journal of Neurophysiology, vol. 70, no. 4, pp. 1401-1411.
Nunez-Abades, P. A. ; Spielmann, J. M. ; Barrionuevo, G. ; Cameron, William. / In vitro electrophysiology of developing genioglossal motoneurons in the rat. In: Journal of Neurophysiology. 1993 ; Vol. 70, No. 4. pp. 1401-1411.
@article{c682162500cd447a82acc5d044d8bfda,
title = "In vitro electrophysiology of developing genioglossal motoneurons in the rat",
abstract = "1. Experiments were performed to determine the change in membrane properties of genioglossal (GG) motoneurons during development. Intracellular recordings were made in 127 GG motoneurons from rats postnatal ages 1-30 days. 2. The input resistance (R(in)) and the membrane time constant (τ(m)) decreased between 5-6 and 13-15 days from 84.8 ± 25.4 (SD) to 47.0 ± 18.9 MΩ (P <0.01) and from 10.0 ± 4.2 to 7.3 ± 3.3 ms (P <0.05), respectively. During this period, the rheobase (I(rh)) increased (P <0.01) from 0.13 ± 0.07 to 0.27 ± 0.14 nA, and the percentage of cells exhibiting inward rectification increased from 5 to 40{\%}. Voltage threshold (V(thr)) of the action potential remained unchanged postnatally. 3. There was also a postnatal change in the shape of the action potential. Specifically, between 1-2 and 5-6 days, there was a decrease (P <0.05) in the spike half-width from 2.23 ± 0.53 to 1.45 ± 0.44 ms, resulting, in part, from a steepening (P <0.05) of the slope of the falling phase of the action potential from 21.6 ± 10.1 to 32.9 ± 13.1 mV/ms. The slope of the rising phase also increased significantly (P <0.01) between 1-2 and 13-15 days from 68.4 ± 31.0 to 91.4 ± 44.3 mV/ms. 4. The average duration of the medium afterhyperpolarization (mAHP(dur)) decreased (P <0.05) between 1-2 (193 ± 53 ms) and 5-6 days (159 ± 43 ms). Whereas the mAHP(dur) was found to be independent of membrane potential, there was a linear relationship between the membrane potential and the amplitude of the medium AHP (mAHP(amp)). From this latter relationship, a reversal potential for the mAHP(amp) was extrapolated to be -87 mV. No evidence for the existence of a slow AHP was found in these developing motoneurons. 5. All cells analyzed (n = 74) displayed adaptation during the first three spikes. The subsequent firing pattern was classified into two groups, adapting and nonadapting. Cells at birth were all adapting, whereas all cells but two from animals 13 days and older were nonadapting. At the intermediate age (5-6 days), the minority (27{\%}) was adapting and the majority (73{\%}) was nonadapting. 6. The mean slope of primary range for the first interspike interval (1st ISI) was ~90 Hz/nA. This value was similar for both adapting and nonadapting cells and did not change postnatally. However, there was a significantly lower (P <0.01) frequency of the mean ISI for adapting (27.7 ± 8.2 Hz/nA) than for nonadapting cells (36.5 ± 11.6 Hz/nA). During development, there was a trend to increase the maximum firing frequency achieved during sustained current injection. Newborn (1-2 days) motoneurons had a maximal frequency of 25.5 ± 10.1 Hz, whereas motoneurons at 19-30 days fired at 42.2 ± 19.7 Hz. 7. The mean ISI of GG motoneurons exhibited only a single linear frequency-current (f-I) relationship, whereas the 1st ISI in some cells exhibited both a primary and a secondary range. The occurrence of cells having a secondary range of the 1st ISI increased postnatally. 8. We hypothesize that there is a specific developmental sequence for the membrane properties of GG motoneurons in which channels shaping the action potential and afterpotential mature earlier than those channels governing its passive membrane properties.",
author = "Nunez-Abades, {P. A.} and Spielmann, {J. M.} and G. Barrionuevo and William Cameron",
year = "1993",
language = "English (US)",
volume = "70",
pages = "1401--1411",
journal = "Journal of Neurophysiology",
issn = "0022-3077",
publisher = "American Physiological Society",
number = "4",

}

TY - JOUR

T1 - In vitro electrophysiology of developing genioglossal motoneurons in the rat

AU - Nunez-Abades, P. A.

AU - Spielmann, J. M.

AU - Barrionuevo, G.

AU - Cameron, William

PY - 1993

Y1 - 1993

N2 - 1. Experiments were performed to determine the change in membrane properties of genioglossal (GG) motoneurons during development. Intracellular recordings were made in 127 GG motoneurons from rats postnatal ages 1-30 days. 2. The input resistance (R(in)) and the membrane time constant (τ(m)) decreased between 5-6 and 13-15 days from 84.8 ± 25.4 (SD) to 47.0 ± 18.9 MΩ (P <0.01) and from 10.0 ± 4.2 to 7.3 ± 3.3 ms (P <0.05), respectively. During this period, the rheobase (I(rh)) increased (P <0.01) from 0.13 ± 0.07 to 0.27 ± 0.14 nA, and the percentage of cells exhibiting inward rectification increased from 5 to 40%. Voltage threshold (V(thr)) of the action potential remained unchanged postnatally. 3. There was also a postnatal change in the shape of the action potential. Specifically, between 1-2 and 5-6 days, there was a decrease (P <0.05) in the spike half-width from 2.23 ± 0.53 to 1.45 ± 0.44 ms, resulting, in part, from a steepening (P <0.05) of the slope of the falling phase of the action potential from 21.6 ± 10.1 to 32.9 ± 13.1 mV/ms. The slope of the rising phase also increased significantly (P <0.01) between 1-2 and 13-15 days from 68.4 ± 31.0 to 91.4 ± 44.3 mV/ms. 4. The average duration of the medium afterhyperpolarization (mAHP(dur)) decreased (P <0.05) between 1-2 (193 ± 53 ms) and 5-6 days (159 ± 43 ms). Whereas the mAHP(dur) was found to be independent of membrane potential, there was a linear relationship between the membrane potential and the amplitude of the medium AHP (mAHP(amp)). From this latter relationship, a reversal potential for the mAHP(amp) was extrapolated to be -87 mV. No evidence for the existence of a slow AHP was found in these developing motoneurons. 5. All cells analyzed (n = 74) displayed adaptation during the first three spikes. The subsequent firing pattern was classified into two groups, adapting and nonadapting. Cells at birth were all adapting, whereas all cells but two from animals 13 days and older were nonadapting. At the intermediate age (5-6 days), the minority (27%) was adapting and the majority (73%) was nonadapting. 6. The mean slope of primary range for the first interspike interval (1st ISI) was ~90 Hz/nA. This value was similar for both adapting and nonadapting cells and did not change postnatally. However, there was a significantly lower (P <0.01) frequency of the mean ISI for adapting (27.7 ± 8.2 Hz/nA) than for nonadapting cells (36.5 ± 11.6 Hz/nA). During development, there was a trend to increase the maximum firing frequency achieved during sustained current injection. Newborn (1-2 days) motoneurons had a maximal frequency of 25.5 ± 10.1 Hz, whereas motoneurons at 19-30 days fired at 42.2 ± 19.7 Hz. 7. The mean ISI of GG motoneurons exhibited only a single linear frequency-current (f-I) relationship, whereas the 1st ISI in some cells exhibited both a primary and a secondary range. The occurrence of cells having a secondary range of the 1st ISI increased postnatally. 8. We hypothesize that there is a specific developmental sequence for the membrane properties of GG motoneurons in which channels shaping the action potential and afterpotential mature earlier than those channels governing its passive membrane properties.

AB - 1. Experiments were performed to determine the change in membrane properties of genioglossal (GG) motoneurons during development. Intracellular recordings were made in 127 GG motoneurons from rats postnatal ages 1-30 days. 2. The input resistance (R(in)) and the membrane time constant (τ(m)) decreased between 5-6 and 13-15 days from 84.8 ± 25.4 (SD) to 47.0 ± 18.9 MΩ (P <0.01) and from 10.0 ± 4.2 to 7.3 ± 3.3 ms (P <0.05), respectively. During this period, the rheobase (I(rh)) increased (P <0.01) from 0.13 ± 0.07 to 0.27 ± 0.14 nA, and the percentage of cells exhibiting inward rectification increased from 5 to 40%. Voltage threshold (V(thr)) of the action potential remained unchanged postnatally. 3. There was also a postnatal change in the shape of the action potential. Specifically, between 1-2 and 5-6 days, there was a decrease (P <0.05) in the spike half-width from 2.23 ± 0.53 to 1.45 ± 0.44 ms, resulting, in part, from a steepening (P <0.05) of the slope of the falling phase of the action potential from 21.6 ± 10.1 to 32.9 ± 13.1 mV/ms. The slope of the rising phase also increased significantly (P <0.01) between 1-2 and 13-15 days from 68.4 ± 31.0 to 91.4 ± 44.3 mV/ms. 4. The average duration of the medium afterhyperpolarization (mAHP(dur)) decreased (P <0.05) between 1-2 (193 ± 53 ms) and 5-6 days (159 ± 43 ms). Whereas the mAHP(dur) was found to be independent of membrane potential, there was a linear relationship between the membrane potential and the amplitude of the medium AHP (mAHP(amp)). From this latter relationship, a reversal potential for the mAHP(amp) was extrapolated to be -87 mV. No evidence for the existence of a slow AHP was found in these developing motoneurons. 5. All cells analyzed (n = 74) displayed adaptation during the first three spikes. The subsequent firing pattern was classified into two groups, adapting and nonadapting. Cells at birth were all adapting, whereas all cells but two from animals 13 days and older were nonadapting. At the intermediate age (5-6 days), the minority (27%) was adapting and the majority (73%) was nonadapting. 6. The mean slope of primary range for the first interspike interval (1st ISI) was ~90 Hz/nA. This value was similar for both adapting and nonadapting cells and did not change postnatally. However, there was a significantly lower (P <0.01) frequency of the mean ISI for adapting (27.7 ± 8.2 Hz/nA) than for nonadapting cells (36.5 ± 11.6 Hz/nA). During development, there was a trend to increase the maximum firing frequency achieved during sustained current injection. Newborn (1-2 days) motoneurons had a maximal frequency of 25.5 ± 10.1 Hz, whereas motoneurons at 19-30 days fired at 42.2 ± 19.7 Hz. 7. The mean ISI of GG motoneurons exhibited only a single linear frequency-current (f-I) relationship, whereas the 1st ISI in some cells exhibited both a primary and a secondary range. The occurrence of cells having a secondary range of the 1st ISI increased postnatally. 8. We hypothesize that there is a specific developmental sequence for the membrane properties of GG motoneurons in which channels shaping the action potential and afterpotential mature earlier than those channels governing its passive membrane properties.

UR - http://www.scopus.com/inward/record.url?scp=0027379257&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0027379257&partnerID=8YFLogxK

M3 - Article

C2 - 8283205

AN - SCOPUS:0027379257

VL - 70

SP - 1401

EP - 1411

JO - Journal of Neurophysiology

JF - Journal of Neurophysiology

SN - 0022-3077

IS - 4

ER -