Calcium activated conductance in skate electroreceptors. Current clamp experiments

W. T. Clusin, Michael V. L. Bennett

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

When current clamped, skate electroreceptor epithelium produces large action potentials in response to stimuli that depolarize the lumenal faces of the receptor cells. With increasing stimulus strength these action potentials become prolonged. When the peak voltage exceeds about 140 mV the repolarizing phase is blocked until the end of the stimulus. Perfusion experiments show that the rising phase of the action potential results from an increase in calcium permeability in the lumenal membranes. Perfusion of the lumen with cobalt or with a zero calcium solution containing EGTA blocks the action potential. Perfusion of the lumen with a solution containing 10 mM Ca and 20 mM EGTA initially slows the repolarizing process at all voltages and lowers the potential at which it is blocked. With prolonged perfusion, repolarization is blocked at all voltages. When excitability is abolished by perfusion with cobalt, or with a zero calcium solution containing EGTA, no delayed rectification occurs. The authors suggest that repolarization during the action potential depends on an influx of calcium into the cytoplasm, and that the rate of repolarization depends on the magnitude of the inward calcium current. Increasingly large stimuli reduce the rate of repolarization by reducing the driving force for calcium, and then block repolarization by causing the lumenal membrane potential to exceed E(Ca). Changes in extracellular calcium affect repolarization in a manner consistent with the resulting change in E(Ca).

Original languageEnglish (US)
Pages (from-to)121-143
Number of pages23
JournalJournal of General Physiology
Volume69
Issue number2
StatePublished - 1977

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Calcium
Action Potentials
Perfusion
Egtazic Acid
Cobalt
Membrane Potentials
Permeability
Cytoplasm
Epithelium
Membranes

ASJC Scopus subject areas

  • Physiology

Cite this

Calcium activated conductance in skate electroreceptors. Current clamp experiments. / Clusin, W. T.; Bennett, Michael V. L.

In: Journal of General Physiology, Vol. 69, No. 2, 1977, p. 121-143.

Research output: Contribution to journalArticle

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