Biphasic effect of tetraethylammonium on canine Purkinje fibre action potential configuration

P. Nánási, Timothy K. Knilans, Ira S. Richards, A. Varró, David A. Lathrop

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

1. 1. Using conventional microelectrode techniques a biphasic effect of tetraethylammonium (5 mmol/l) on the configuration of action potentials recorded from isolated canine Purkinje fibres: action potentials were first shortened (early effect) and then lengthened (late effect) by tetraethylammonium. 2. 2. The early effect of tetraethylammonium also included lengthening of phase 1 duration and elevation of the plateau amplitude. These early effects reached steady-state within the first 3 min of superfusion and were readily reversed within 3 min of initiating washout of the drug. 3. 3. The late effect (gradual lengthening of repolarisation during phase 3) failed to reach steady-state within the initial 60 min of superfusion and was not reversible. 4. 4. The early effects of tetraethylammonium were more marked at slow driving rates and were not affected by blockade of α- and β-adrenoceptors using 1 μmol/l phentolamine and 1 μmol/l propranolol. 5. 5. The early effects of tetraethylammonium were mimicked by 4-aminopyridine (0.5 mmol/l), and in the presence of 4-aminopyridine tetraethylammonium failed to induce further changes in action potential morphology. 6. 6. The early effects of tetraethylammonium may be due to inhibition of the transient outward current. 7. 7. The rapid onset and reversibility of these early effects suggest that tetraethylammonium may act from outside the cell membrane.

Original languageEnglish
Pages (from-to)733-738
Number of pages6
JournalGeneral Pharmacology
Volume23
Issue number4
DOIs
Publication statusPublished - 1992

Fingerprint

Purkinje Fibers
Tetraethylammonium
Action Potentials
Canidae
4-Aminopyridine
Phentolamine
Microelectrodes
Propranolol
Adrenergic Receptors
Cell Membrane

ASJC Scopus subject areas

  • Pharmacology

Cite this

Biphasic effect of tetraethylammonium on canine Purkinje fibre action potential configuration. / Nánási, P.; Knilans, Timothy K.; Richards, Ira S.; Varró, A.; Lathrop, David A.

In: General Pharmacology, Vol. 23, No. 4, 1992, p. 733-738.

Research output: Contribution to journalArticle

Nánási, P. ; Knilans, Timothy K. ; Richards, Ira S. ; Varró, A. ; Lathrop, David A. / Biphasic effect of tetraethylammonium on canine Purkinje fibre action potential configuration. In: General Pharmacology. 1992 ; Vol. 23, No. 4. pp. 733-738.
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