Effects of streptozotocin-induced diabetes on contraction and calcium transport in rat ventricular cardiomyocytes

Nicholas Bracken, Frank C. Howarth, Jaipaul Singh

Research output: Chapter in Book/Report/Conference proceedingConference contribution

27 Citations (Scopus)

Abstract

Cardiovascular diseases are the major cause of morbidity and mortality in diabetic patients. Contractile function of the heart is frequently compromised in the clinical setting and in experimental models of diabetes mellitus (DM). This article investigated the effect of streptozotocin (STZ)-induced type 1 DMon contraction, L-type calcium (Ca2+) current (ICa2+L), and on cytosolic calcium concentrations [Ca2+]i in ventricular myocytes of the rat heart. After 4-10 weeks of STZ treatment, blood glucose levels in diabetic animals were significantly (P < 0.05) higher compared to age-matched controls. Diabetic rats have significantly (P < 0.05) reduced body, reduced heart weight, and reduced viability of ventricular myocytes compared to controls. The amplitude of ICa2+L and amplitude of contraction were significantly reduced (P < 0.05) at test potentials in the range -10 mV to +20 mV and -30 mV to +40 mV, respectively, in myocytes from diabetic animals compared to age-matched controls. Moreover, there was a significant (P < 0.05) delay in electrically stimulated and caffeine-evoked time to half relaxation of the Ca2+ transient in myocytes from diabetic animals compared to controls. A similar effect was obtained in myocytes treated with a combination of caffeine and nickel chloride (NiCl2). It is concluded that the diabetes-induced voltage-dependent decrease in contraction is associated with reduced Ca2+ channel activities and prolonged diastolic cytosolic Ca2+ compared to age-matched control. Taken together, the results suggest that Ca2+ homeostasis is deranged during DM and this may be expressed at the level of the Na+/Ca 2+ exchanger.

Original languageEnglish
Title of host publicationDiabetes Mellitus and Its Complications
Subtitle of host publicationMolecular Mechanisms, Epidemiology, and Clinical Medicine
PublisherBlackwell Publishing Inc.
Pages208-222
Number of pages15
ISBN (Print)1573316350, 9781573316354
DOIs
Publication statusPublished - Nov 2006

Publication series

NameAnnals of the New York Academy of Sciences
Volume1084
ISSN (Print)0077-8923
ISSN (Electronic)1749-6632

Keywords

  • Calcium
  • Contraction
  • Diabetes
  • Heart
  • Rat
  • Streptozotocin
  • Ventricular myocytes

ASJC Scopus subject areas

  • Neuroscience(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • History and Philosophy of Science

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