Action potentials and potassium currents in rat ventricular muscle during experimental diabetes

J. Magyar, Z. Rusznák, P. Szentesi, G. Szücs, L. Kovács

Research output: Contribution to journalArticle

105 Citations (Scopus)

Abstract

Time course of the surface electrical activity was studied in left ventricular trabeculae of Wistar rats made diabetic using streptozotocin. The action potentials were recorded in Tyrode's solution at 32°C, their duration considerably increased in diabetes. By the 8th week, the prolongation was 64% at 25% of repolarization; 112% at 50% and 118% at 75%. Insulin treatment reduced the prolongation of the action potentials although a complete restoration was not achieved. 0.1 mm La3+ moderately shortened the electrical activity both in control and in diabetic trabeculae. Three mm 4-aminopyridine made the time course of control action potentials very similar to the diabetic ones while the action potentials from the diabetic animals were prolonged further to a smaller extent. Whole-cell clamp experiments in isolated ventricular myocytes (20-23°C) showed a considerable decrease and a somewhat accelerated inactivation of the transient outward current (Ito) in diabetes. The steady-state inactivation and the rate of recovery from inactivation of Ito did not change. No alterations in the magnitude and voltage dependence of inward rectifier (IKl) were found around the resting membrane potential. The diabetes-related suppression of Ito explains the decreased repolarization rate of action potentials.

Original languageEnglish
Pages (from-to)841-853
Number of pages13
JournalJournal of Molecular and Cellular Cardiology
Volume24
Issue number8
DOIs
Publication statusPublished - 1992

Fingerprint

Action Potentials
Potassium
Muscles
4-Aminopyridine
Streptozocin
Membrane Potentials
Muscle Cells
Wistar Rats
Insulin

Keywords

  • 4-aminopyridine
  • Action potentials
  • Experimental diabetes
  • Inward rectifier
  • Isolated ventricular myocytes
  • La
  • Rat left ventricular trabeculae
  • Transient outward current

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

Cite this

Action potentials and potassium currents in rat ventricular muscle during experimental diabetes. / Magyar, J.; Rusznák, Z.; Szentesi, P.; Szücs, G.; Kovács, L.

In: Journal of Molecular and Cellular Cardiology, Vol. 24, No. 8, 1992, p. 841-853.

Research output: Contribution to journalArticle

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