Effect of the flavonoid galangin on urinary bladder rat contractility in-vitro

Galangin is a flavanol with several biological activities. We have evaluated the effect of galangin on the contractile response elicited by electrical field stimulation (EFS) in the rat isolated urinary bladder. Galangin (10(-8)-10(-4)m) produced a concentration-de pendent inhibition of the EFS contractile response without modifying the contractions produced by exogenous acetylcholine (10(-6) m). Blockade of adrenergic and cholinergic nerves with a combination of atropine (10(-6) M), phentolamine (10(-6) m) and propranolol (10(-6) m) or blockade of tachykinin NK1, and NK2 receptors with SR140333 (10(-7) m) and SR48968 (10(-6) m) did not modify the inhibitory effect of galangin. However, verapamil (10(-7) m) significantly reduced the inhibitory effect of galangin. It is concluded that the galangin inhibits EFS-induced contractions of the rat urinary bladder by acting on L-type calcium channels on presynaptic nerves.