Diosmin‐induced increase in sensitivity to Ca2+ of the smooth muscle contractile apparatus in the rat isolated femoral vein

Abstract

The effect of diosmin, a flavone derivative, on the Ca2+ sensitivity of the venous contractile apparatus was investigated in chemically (β‐escin) skinned strips from the rat isolated femoral vein. Diosmin (0.5–10 μm) shifted to the left the concentration‐response curve to Ca2+ (0.05–5 μm). The maximal effect was observed in the presence of 1 μm diosmin which increased the contractile response evoked by 0.15 μm Ca2+ from 26.3% to 78.9% of the maximal Ca2+‐induced response. This work demonstrates that the venotonic action of diosmin involves an increase in the Ca2+ sensitivity of the contractile apparatus. Such a mechanism of action could represent a new and important means of therapeutic control of vasomotor activity. 1994 British Pharmacological Society