Spasmolytic Action of Centaurium erythraea on Rabbit Jejunum is through Calcium Channel Blockade and NO Release

Abstract

Objective: The aim of the present study was to assess the antispasmodic effect of the aqueous extract from aerial parts of Centaurium erythraea (AECE) on isolated rabbit jejunum. Methods: Myorelaxant and spasmolytic effects of AECE (0.3-10 mg/ml) were tested directly on spontaneous contractions and after spasm induction. To evaluate whether the effect of AECE involves a Ca2+ channel blockade, the tissues were placed in Ca2+-free Tyrode’s solution, then calcium was added in the presence of AECE. In addition, to investigate the involvement of the NO /cGMP pathway in the spasmolytic effect of AECE, the concentration-effect curve was achieved in the presence of L-NAME as a nitric oxide synthesis inhibitor, or ODQ as a specific cGMP inhibitor. Results: Aqueous extract of Centaurium erythraea significantly reduced the jejunum’s spontaneous contractions (p<0.05). When the jejunum was incubated in Ca2+-free Tyrode’s solution or in high K+-Ca2+-free Tyrode’s solution, AECE significantly inhibited the recovery of spontaneous contraction as well as those induced by high K+ during Ca2+ supplementation. Also, AECE shifted to the right the concentration responses curve of high K+ induced jejunum contraction similarly to the effect produced by verapamil, a known calcium channel blocker, suggesting a presence of calcium antagonistic constituent(s) in AECE. By contrast, pretreatment with L-NAME or ODQ significantly reduced the antispasmodic effect, and shifted to the right the response curves of AECE, demonstrating the involvement of the NO pathway in this effect. Conclusion: The main finding of our work suggests that AECE contains spasmolytic constituents mediating their effect at least through Ca2+ influx blockade and NO-cGMP pathway activation.