Potential vascular α1-adrenoceptor blocking properties of metformin in rat aorta and tail artery

Abstract

Metformin is a widely used drug for the treatment of type 2 Diabetes Mellitus. Several studies have also suggested that metformin decreases blood pressure; although an interaction with alpha(1)-adrenoceptors has been proposed, this mechanism needs to be further investigated. Since alpha(1)-adrenoceptors play a significant role to regulate vascular tone, this study has analysed the potential ability of metformin to block alpha(1-)adrenoceptors in rat aorta and tail artery. For this purpose, the contractile responses induced by noradrenaline, methoxamine, and phenylephrine were determined in the absence or presence of metformin in rat aorta and tail artery rings. In both arteries, noradrenaline, methoxamine, and phenylephrine produced concentration-dependent contractile responses. Interestingly, the contractile responses to noradrenaline, methoxamine, and phenylephrine were significantly and differentially blocked by metformin (1, 3.1 and/or 10 mM) but not by vehicle. These results suggest that metformin is capable to block alpha(1)-adrenoceptors and may explain, at least in part, the anti-hypertensive effect observed in several clinical trials.