Characteristics of voltage-dependent conductance in the membranes of a non-excitable tissue: The amphibian lens

Nicholas A Delamere, G. Duncan, C. A. Paterson

Research output: Contribution to journalArticle

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Abstract

The electrical conductance of the frog lens membranes was observed to increase when the lens was depolarized by current, and to decrease when the lens was hyperpolarized. The total lens conductance (G(T)) could be described by a voltage-dependent component (G(H)) together with a voltage-insensitive component (G(O)). Conductance measured at the resting potential increased from 9.7 to 14.4 x 10-5S when the lens was depolarized by 9.1 mV in 10-4 M-ouabain. The increase of conductance could be explained by an increase of G(H) which resulted from the depolarization alone. Potassium-rich solutions influenced the conductance by increasing G(H) as the result of depolarization and by decreasing (blocking) G(O). Small increases in the external potassium concentration (from 2.5 to 5 mM), which did not depolarize the lens, resulted in a decrease in resting conductance due to the blockade of G(O). Conductance-voltage relationships established in 2.5 (control), 5, 12.5 and 25 mM external potassium could each be fitted to a single mathematical model by assuming that GO had been reduced from 5.0 (control) to 4.5, 3 and 1 x 10-5S respectively by those increased potassium concentrations. Barium (2 mM) depolarized the lens by 14.3 mV and decreased the resting conductance by 39%. When the lens was depolarized by a step current pulse in the presence of barium, the conductance increased with time after the onset of the current. Hyperpolarization elicited less time dependence of the conductance. Barium reduced the extent to which lens conductance was dependent on voltage.

Original languageEnglish (US)
Pages (from-to)49-59
Number of pages11
JournalJournal of Physiology
VolumeVOL. 308
StatePublished - 1980
Externally publishedYes

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Amphibians
Lenses
Membranes
Potassium
Barium
Ouabain
Anura
Membrane Potentials
Theoretical Models

ASJC Scopus subject areas

  • Physiology

Cite this

Characteristics of voltage-dependent conductance in the membranes of a non-excitable tissue : The amphibian lens. / Delamere, Nicholas A; Duncan, G.; Paterson, C. A.

In: Journal of Physiology, Vol. VOL. 308, 1980, p. 49-59.

Research output: Contribution to journalArticle

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abstract = "The electrical conductance of the frog lens membranes was observed to increase when the lens was depolarized by current, and to decrease when the lens was hyperpolarized. The total lens conductance (G(T)) could be described by a voltage-dependent component (G(H)) together with a voltage-insensitive component (G(O)). Conductance measured at the resting potential increased from 9.7 to 14.4 x 10-5S when the lens was depolarized by 9.1 mV in 10-4 M-ouabain. The increase of conductance could be explained by an increase of G(H) which resulted from the depolarization alone. Potassium-rich solutions influenced the conductance by increasing G(H) as the result of depolarization and by decreasing (blocking) G(O). Small increases in the external potassium concentration (from 2.5 to 5 mM), which did not depolarize the lens, resulted in a decrease in resting conductance due to the blockade of G(O). Conductance-voltage relationships established in 2.5 (control), 5, 12.5 and 25 mM external potassium could each be fitted to a single mathematical model by assuming that GO had been reduced from 5.0 (control) to 4.5, 3 and 1 x 10-5S respectively by those increased potassium concentrations. Barium (2 mM) depolarized the lens by 14.3 mV and decreased the resting conductance by 39{\%}. When the lens was depolarized by a step current pulse in the presence of barium, the conductance increased with time after the onset of the current. Hyperpolarization elicited less time dependence of the conductance. Barium reduced the extent to which lens conductance was dependent on voltage.",
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