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.