Diabetes Research Today is a free monthly online journal that collates and summarizes the latest research about Diabetes, including details on insulin, type i, type ii, diet, treatment, prevention.

The role of gender differences in beta-adrenergic receptor responsiveness of diabetic rat heart.

Bilginoglu A, Cicek FA, Ugur M, Gurdal H, Turan B

Department of Biophysics, School of Medicine, Ankara University, Ankara, Turkey.

Since the mechanisms responsible for gender differences in cardiac contractile function have not been fully elucidated, we focused to determine the effect of gender difference on beta-adrenergic receptors (beta-ARs) signal transduction in ventricular cardiomyocytes from insulin-dependent diabetic (streptozotocin-induced) rats. Dose-response curves of left ventricular developed pressure (LVDP) to isoproterenol (ISO) in females showed that there was only a approximately 30% decrease in the maximum response without a significant shift in EC50 in diabetic females. On the other hand, diabetes induced a clear rightward shift in the potency (5-10 folds) without a significant change in the maximum response in the males. In order to further determine of the underlying mechanism for this difference, we measured cAMP production and obtained dose-response curves with ISO stimulation in isolated cardiomyocytes. In diabetic females, there was no obvious change in the cAMP dose-response curve. On the other hand, there was a significant decrease in the maximum response without any apparent change in the potency of diabetic males. Our findings indicate that male and female rats are affected differently by diabetes in terms of LVDP responses to beta-ARs stimulation. Also, the difference between their beta-ARs induced cAMP responses may underlie this disparity.

Published 2 October 2007 in Mol Cell Biochem, 305(1): 63-9.
Full-text of this article is available online (may require subscription).

© 2004-2008 Diabetes Research Today. All Rights Reserved.