HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 294/4/H1609    most recent 00949.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Sharma, V. Articles by McNeill, J. H. Search for Related Content PubMed PubMed Citation Articles by Sharma, V. Articles by McNeill, J. H.

Metoprolol improves cardiac function and modulates cardiac metabolism in the streptozotocin-diabetic rat

¹Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, University of British Columbia; ²Department of Pathology and Laboratory Medicine, James Hogg iCapture Centre for Pulmonary and Cardiovascular Research, St. Paul's Hospital; and ³Department of Biochemistry and Molecular Biology, Diabetes Research Group, Life Sciences Institute, Life Sciences Centre, University of British Columbia, Vancouver, Canada

Submitted 15 August 2007 ; accepted in final form 17 January 2008

The effects of diabetes on heart function may be initiated or compounded by the exaggerated reliance of the diabetic heart on fatty acids and ketones as metabolic fuels. β-Blocking agents such as metoprolol have been proposed to inhibit fatty acid oxidation. We hypothesized that metoprolol would improve cardiac function by inhibiting fatty acid oxidation and promoting a compensatory increase in glucose utilization. We measured ex vivo cardiac function and substrate utilization after chronic metoprolol treatment and acute metoprolol perfusion. Chronic metoprolol treatment attenuated the development of cardiac dysfunction in streptozotocin (STZ)-diabetic rats. After chronic treatment with metoprolol, palmitate oxidation was increased in control hearts but decreased in diabetic hearts without affecting myocardial energetics. Acute treatment with metoprolol during heart perfusions led to reduced rates of palmitate oxidation, stimulation of glucose oxidation, and increased tissue ATP levels. Metoprolol lowered malonyl-CoA levels in control hearts only, but no changes in acetyl-CoA carboxylase phosphorylation or AMP-activated protein kinase activity were observed. Both acute metoprolol perfusion and chronic in vivo metoprolol treatment led to decreased maximum activity and decreased sensitivity of carnitine palmitoyltransferase I to malonyl-CoA. Metoprolol also increased sarco(endo)plasmic reticulum Ca²⁺-ATPase expression and prevented the reexpression of atrial natriuretic peptide in diabetic hearts. These data demonstrate that metoprolol ameliorates diabetic cardiomyopathy and inhibits fatty acid oxidation in streptozotocin-induced diabetes. Since malonyl-CoA levels are not increased, the reduction in total carnitine palmitoyltransferase I activity is the most likely factor to explain the decrease in fatty acid oxidation. The metabolism changes occur in parallel with changes in gene expression.

diabetic cardiomyopathy; fatty acid oxidation; heart failure; carnitine palmitoyltransferase; malonyl-coenzyme A

This article has been cited by other articles:

				A. P. Kellogg, K. Converso, T. Wiggin, M. Stevens, and R. Pop-Busui Effects of cyclooxygenase-2 gene inactivation on cardiac autonomic and left ventricular function in experimental diabetes Am J Physiol Heart Circ Physiol, February 1, 2009; 296(2): H453 - H461. [Abstract] [Full Text] [PDF]