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MUSCLE CELL BIOLOGY AND CELL MOTILITY
Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
Submitted 28 February 2005 ; accepted in final form 12 May 2006
Diabetes mellitus (DM) causes the development of a specific cardiomyopathy that results from the metabolic derangements present in DM and manifests as cardiac contractile dysfunction. Although myocardial dysfunction in Type 1 DM has been associated with defects in the function and regulation of the sarcoplasmic reticulum (SR), very little is known about SR function in Type 2 DM. Accordingly, this study examined whether abnormalities in cardiac contractile performance and SR function occur in the prestage of Type 2 DM (i.e., during insulin resistance). Sucrose feeding was used to induce whole body insulin resistance, whereas cardiac contractile performance was assessed by echocardiography and SR function was measured by SR calcium (Ca2+) uptake. Sucrose-fed rats exhibited hyperinsulinemia, hyperglycemia, and hyperlipidemia relative to control rats. Serial echocardiographic assessments in the sucrose-fed rats revealed early abnormalities in diastolic function followed by late systolic dysfunction and concurrent alterations in myocardial structure. The hearts of the 10-wk sucrose-fed rats showed depressed SR function demonstrated by a significant reduction in SR Ca2+ uptake. The decline in SR Ca2+ uptake was associated with a significant decrease in the cAMP-dependent protein kinase and Ca2+/calmodulin-dependent protein kinase II-mediated phosphorylation of phospholamban. The results show that abnormalities in cardiac contractile performance and SR function occur at an insulin-resistant stage before the manifestation of overt Type 2 DM.
cardiomyopathy; diabetes mellitus; echocardiography
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S. A. Marsh, L. J. Dell'Italia, and J. C. Chatham Interaction of diet and diabetes on cardiovascular function in rats Am J Physiol Heart Circ Physiol, February 1, 2009; 296(2): H282 - H292. [Abstract] [Full Text] [PDF] |
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