Exp Clin Endocrinol Diabetes 2003; 111(3): 139-145
DOI: 10.1055/s-2003-39786
Article

J. A. Barth Verlag in Georg Thieme Verlag Stuttgart · New York

Insulin-Like Effect of Low-Dose Leptin on Glucose Transport in Langendorff Rat Hearts

M. Haap 1 , B. Houdali 1 , E. Maerker 1 , W. Renn 1 , F. Machicao 1 , H. M. Hoffmeister 2 , H.-U. Häring 1 , K. Rett 3
  • 1Department of Endocrinology, Metabolism and Pathobiochemistry, Eberhard-Karls-University Tuebingen, Germany
  • 2Department of Cardiology, Eberhard-Karls-University Tuebingen, Germany
  • 3German Clinic for Diagnostics, Wiesbaden, Germany
Weitere Informationen

Publikationsverlauf

Received: June 11, 2002 First decision: July 23, 2002

Accepted: November 24, 2002

Publikationsdatum:
04. Juni 2003 (online)

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Abstract

Background

In a murine myotube cell line (C2C12 myotubes), leptin at low physiological concentrations (1 ng/ml) has been shown to stimulate glucose transport and glycogen synthesis. The aim of the present study was to test whether an analogous leptin effect on glucose transport is detectable in the heart.

Methods and Results

We used the isolated Langendorff rat heart preparation with hemodynamic function control. Using polymerase chain reaction (RT-PCR), a 346- and 375-base fragment indicative for the short and long leptin receptor isoform was detected in the rat heart. Glucose transport rates were calculated using equimolar double tracer perfusion with the non-metabolizable glucose analog 3-O-methylglucose (3-O-MG) and the non-transportable tracer mannitol and two-compartimental modeling. 3-O-MG uptake at a perfusate glucose concentration of 11 mM was measured over 15 minutes in control hearts, hearts perfused with insulin (10 mU/ml), leptin (1 ng/ml) or insulin (10 mU/ml) plus leptin (1 ng/ml; n = 8 in each group). The basal 3-O-MG transport rate of 0,7351 ± 0,051 µmol/min/g wet weight was increased 4.18fold with insulin, 2.69fold with leptin, and 4.2fold with leptin plus insulin. Simultaneous monitoring of hemodynamic function revealed a minor and transient effect of leptin on left ventricular pressure, which was strongly augmented in coperfusion with insulin.

Conclusion

The data suggest that leptin at low physiological concentrations is able to exert a partial insulin like effect on glucose uptake. We speculate that the effect might be mediated by both leptin receptor isoforms.This leptin effect is additive to the effect of insulin and might therefore contribute to the insulin independent basal glucose supply of the heart. It can not be completely excluded that the observed leptin effect on glucose transport is secondary to altered myocardial function.

References

Prof. H.-U. Häring

Eberhard-Karls-Universität Tübingen
Department of Endocrinology, Metabolism and Pathobiochemistry

Otfried-Müller-Str. 10

72076 Tübingen

Germany

Telefon: +49 7071 2983670

Fax: +49 7071 292784

eMail: mmhaap@med.uni-tuebingen.de