Ferulic acid suppresses guinea pig ileal longitudinal smooth muscle contractions by inhibiting voltage-dependent Ca2+ channels.

We investigated the effects of ferulic acid (FA) on contractions in guinea pig ileal longitudinal smooth muscle (ILSM). FA (3 × 10-4-3 × 10-3 M) inhibited ILSM contractions induced by acetylcholine, histamine, prostaglandin F2α, and serotonin concentration-dependently, reversibly, and noncompetitively with pD'2 values of ∼3. FA also concentration-dependently and reversibly inhibited KCl-induced ILSM contractions. FA (10-3 M), which inhibited ILSM contractions by ∼50 %, also reduced verapamil-sensitive, KCl-induced intracellular Ca2+ increases in A7r5 cells by ∼35 %. These results suggest that FA inhibits ILSM contraction, primarily through the reversible inhibition of Ca2+ influx via voltage-dependent Ca2+ channels.