Streptozotocin diabetes protects against arrhythmias in rat isolated hearts: Role of hypothyroidism

Liqun Zhang, James R. Parratt, Graham H. Beastall, Nigel J. Pyne, Brian L. Furman

Research output: Contribution to journalArticle

33 Citations (Scopus)


We examined the contribution of hypothyroidism to streptozotocin diabetes-induced alterations in the arrhythmia susceptibility of ex vivo hearts to regional zero-flow ischaemia. Diabetic rats received either protamine zinc insulin (10 IU/kg/day, s.c.) or triiodothyronine (10 μg/kg/day, s.c.) for 8 weeks commencing 72 h after injection of streptozotocin (60 mg/kg, i.p.). Arrhythmias were determined in ex vivo Langendorff-perfused hearts, subjected to a 30-min main left coronary artery occlusion, followed by 30-min reperfusion. Serum free thyroxine concentrations, rectal temperature and ex vivo heart rate were significantly decreased in the 8-week diabetic group (P < 0.001). These changes were prevented by administration of triiodothyronine or insulin. Ventricular fibrillation during reperfusion was abolished in hearts from diabetic rats. This protection was prevented by treatment with either triiodothyronine or insulin. Hearts from methimazole-hypothyroid rats also showed no ventricular fibrillation during reperfusion. The protection against ischaemia-reperfusion-arrhythmias observed in hearts from streptozotocin-diabetic rats may be due to diabetes-induced hypothyroidism.

Original languageEnglish
Pages (from-to)269-276
Number of pages8
JournalEuropean Journal of Pharmacology
Issue number2-3
Publication statusPublished - Jan 25 2002


  • Arrhythmias
  • Diabetes
  • Heart, ex vivo
  • Hypothyroidism
  • Ischaemia-reperfusion, rat
  • Streptozotocin

ASJC Scopus subject areas

  • Pharmacology

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