Anisotropic ion diffusivity in intervertebral disc

An electrical conductivity approach

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

STUDY DESIGN. Investigation of the transport behavior of ions in intervertebral disc using an electrical conductivity method. OBJECTIVES. To determine the electrical conductivity and ion diffusivity of nucleus pulposus and anulus fibrosus in 3 major directions (axial, circumferential, and radial). SUMMARY OF BACKGROUND DATA. Knowledge of diffusivity of small molecules is important for understanding nutrition supply in intervertebral disc and disc degeneration. However, little is known on the anisotropic behaviors of ion diffusivity and of electrical conductivity in intervertebral disc. METHODS. Electrical conductivity measurement was performed on 24 axial, circumferential, and radial anulus fibrosus specimens and 24 axial nucleus pulposus specimens from bovine coccygeal discs. The diffusivity of Na and Cl were estimated by the analysis of conductivity data. RESULTS. The electrical conductivity (mean ± standard deviation; n = 24) of the bovine anulus fibrosus was 4.70 ± 1.08 mS/cm in the axial, 2.86 ± 0.83 mS/cm in the radial, and 4.38 ± 1.25 mS/cm in the circumferential direction. For nucleus pulposus, the electrical conductivity (mean ± standard deviation; n = 24) was 8.95 ± 0.89 mS/cm. The mean value for nucleus pulposus was significantly higher than that of anulus fibrosus (t test, P < 0.05). For anulus fibrosus, the conductivity in the radial direction was significantly lower than in axial or circumferential directions. Similar trends were found for both Na and Cl diffusivities. Both electrical conductivity and ion diffusivity were highly sensitive to water content. CONCLUSIONS. Electrical conductivity and ion diffusivity of anulus fibrosus are anisotropic.

Original languageEnglish
Pages (from-to)2783-2789
Number of pages7
JournalSpine
Volume31
Issue number24
DOIs
StatePublished - Nov 1 2006

Fingerprint

Electric Conductivity
Intervertebral Disc
Ions
Intervertebral Disc Degeneration
Ion Transport
Annulus Fibrosus
Direction compound
Nucleus Pulposus
Water

Keywords

  • Anisotropic
  • Annulus fibrosis
  • Electrical conductivity
  • Ion diffusion coefficient
  • Nucleus pulposus
  • Spine

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Orthopedics and Sports Medicine

Cite this

Anisotropic ion diffusivity in intervertebral disc : An electrical conductivity approach. / Jackson, Alicia Renee; Yao, Hai; Brown, Mark; Gu, Weiyong.

In: Spine, Vol. 31, No. 24, 01.11.2006, p. 2783-2789.

Research output: Contribution to journalArticle

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abstract = "STUDY DESIGN. Investigation of the transport behavior of ions in intervertebral disc using an electrical conductivity method. OBJECTIVES. To determine the electrical conductivity and ion diffusivity of nucleus pulposus and anulus fibrosus in 3 major directions (axial, circumferential, and radial). SUMMARY OF BACKGROUND DATA. Knowledge of diffusivity of small molecules is important for understanding nutrition supply in intervertebral disc and disc degeneration. However, little is known on the anisotropic behaviors of ion diffusivity and of electrical conductivity in intervertebral disc. METHODS. Electrical conductivity measurement was performed on 24 axial, circumferential, and radial anulus fibrosus specimens and 24 axial nucleus pulposus specimens from bovine coccygeal discs. The diffusivity of Na and Cl were estimated by the analysis of conductivity data. RESULTS. The electrical conductivity (mean ± standard deviation; n = 24) of the bovine anulus fibrosus was 4.70 ± 1.08 mS/cm in the axial, 2.86 ± 0.83 mS/cm in the radial, and 4.38 ± 1.25 mS/cm in the circumferential direction. For nucleus pulposus, the electrical conductivity (mean ± standard deviation; n = 24) was 8.95 ± 0.89 mS/cm. The mean value for nucleus pulposus was significantly higher than that of anulus fibrosus (t test, P < 0.05). For anulus fibrosus, the conductivity in the radial direction was significantly lower than in axial or circumferential directions. Similar trends were found for both Na and Cl diffusivities. Both electrical conductivity and ion diffusivity were highly sensitive to water content. CONCLUSIONS. Electrical conductivity and ion diffusivity of anulus fibrosus are anisotropic.",
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N2 - STUDY DESIGN. Investigation of the transport behavior of ions in intervertebral disc using an electrical conductivity method. OBJECTIVES. To determine the electrical conductivity and ion diffusivity of nucleus pulposus and anulus fibrosus in 3 major directions (axial, circumferential, and radial). SUMMARY OF BACKGROUND DATA. Knowledge of diffusivity of small molecules is important for understanding nutrition supply in intervertebral disc and disc degeneration. However, little is known on the anisotropic behaviors of ion diffusivity and of electrical conductivity in intervertebral disc. METHODS. Electrical conductivity measurement was performed on 24 axial, circumferential, and radial anulus fibrosus specimens and 24 axial nucleus pulposus specimens from bovine coccygeal discs. The diffusivity of Na and Cl were estimated by the analysis of conductivity data. RESULTS. The electrical conductivity (mean ± standard deviation; n = 24) of the bovine anulus fibrosus was 4.70 ± 1.08 mS/cm in the axial, 2.86 ± 0.83 mS/cm in the radial, and 4.38 ± 1.25 mS/cm in the circumferential direction. For nucleus pulposus, the electrical conductivity (mean ± standard deviation; n = 24) was 8.95 ± 0.89 mS/cm. The mean value for nucleus pulposus was significantly higher than that of anulus fibrosus (t test, P < 0.05). For anulus fibrosus, the conductivity in the radial direction was significantly lower than in axial or circumferential directions. Similar trends were found for both Na and Cl diffusivities. Both electrical conductivity and ion diffusivity were highly sensitive to water content. CONCLUSIONS. Electrical conductivity and ion diffusivity of anulus fibrosus are anisotropic.

AB - STUDY DESIGN. Investigation of the transport behavior of ions in intervertebral disc using an electrical conductivity method. OBJECTIVES. To determine the electrical conductivity and ion diffusivity of nucleus pulposus and anulus fibrosus in 3 major directions (axial, circumferential, and radial). SUMMARY OF BACKGROUND DATA. Knowledge of diffusivity of small molecules is important for understanding nutrition supply in intervertebral disc and disc degeneration. However, little is known on the anisotropic behaviors of ion diffusivity and of electrical conductivity in intervertebral disc. METHODS. Electrical conductivity measurement was performed on 24 axial, circumferential, and radial anulus fibrosus specimens and 24 axial nucleus pulposus specimens from bovine coccygeal discs. The diffusivity of Na and Cl were estimated by the analysis of conductivity data. RESULTS. The electrical conductivity (mean ± standard deviation; n = 24) of the bovine anulus fibrosus was 4.70 ± 1.08 mS/cm in the axial, 2.86 ± 0.83 mS/cm in the radial, and 4.38 ± 1.25 mS/cm in the circumferential direction. For nucleus pulposus, the electrical conductivity (mean ± standard deviation; n = 24) was 8.95 ± 0.89 mS/cm. The mean value for nucleus pulposus was significantly higher than that of anulus fibrosus (t test, P < 0.05). For anulus fibrosus, the conductivity in the radial direction was significantly lower than in axial or circumferential directions. Similar trends were found for both Na and Cl diffusivities. Both electrical conductivity and ion diffusivity were highly sensitive to water content. CONCLUSIONS. Electrical conductivity and ion diffusivity of anulus fibrosus are anisotropic.

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