Mg2+-Dependent Atpase Activity in Cardiac Myofibrils from The Insulin-Resistant JCR:La-Cp Rat

  • Tarun Misra
  • James C. Russell
  • Tod A. Clark
  • Grant N. Pierce
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 498)


There is a great deal of information presently available documenting a cardiomyopathic condition in insulin-deficient models of diabetes. Less information is available documenting a similar status in non insulin-dependent models of diabetes. We have studied the functional integrity of the myofibrils isolated from hearts of JCR:LA rats. The JCR:LA rat is hyperinsulinemic, hyperlipidemic, glucose intolerant and obese. As such, it carries many of the characteristics found in humans with non insulin-dependent diabetes mellitus. These animals also have many indications of heart disease. However, it is not clear if the hearts suffer from vascular complications or are cardiomyopathic in nature. We examined Mg2+ - dependent myofibrillar ATPase in hearts of JCR:LA-cp/cp rats and their corresponding control animals (+/?) and found no significant differences (P> 0.05). This is in striking contrast to the depression in this activity exhibited by cardiac myofibrils isolated from insulin-deficient models of diabetes. Our data demonstrate that myofibrillar functional integrity is normal in JCR:LA-cp rats and suggest that these hearts are not in a cardiomyopathic state. Insulin status may be critical in generating a cardiomyopathic condition in diabetes.


ATPase Activity Diabetic Cardiomyopathy Myofibrillar Protein Subcellular Organelle Myosin ATPase Activity 
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Copyright information

© Springer Science+Business Media New York 2001

Authors and Affiliations

  • Tarun Misra
    • 1
  • James C. Russell
    • 2
  • Tod A. Clark
    • 1
  • Grant N. Pierce
    • 1
  1. 1.Division of Stroke &Vascular Disease,St. Boniface General Hospital Research Centre, and the Department of PhysiologyUniversity of Manitoba
  2. 2.Department of SurgeryUniversity of AlbertaEdmonton

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