Participation of extracellular calcium in ¦Á-hederin-induced contractions of rat isolated stomach strips

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• 作者：Marta Mendel ; ^{marta_mendel@sggw.pl} ; Magdalena Ch?opecka ; Natalia Dziekan ; Wojciech Karlik ; Maria Wiechetek
• 关键词：¦Á-Hederin ; Smooth muscle ; Verapamil ; Extracellular calcium
• 刊名：Journal of Ethnopharmacology
• 出版年：2013
• 出版时间：7 March, 2013
• 年：2013
• 卷：146
• 期：1
• 页码：423-426
• 全文大小：228 K

文摘

lass=""h4"">Ethnopharmacological relevance

The dry extract of Hedera helix leaves, due to its secretolytic and antispasmodic effects, is commonly used to produce pharmaceuticals applied in case of cough and other respiratory symptoms. The results of some in vitro studies as well as the clinical signs of poisoning caused by Hedera helix suggest however strong contractile effect on smooth muscle. In order to clarify the impact of ¦Á-hederin (the main active agent of ivy extract) on smooth muscle, the origin of activated calcium involved in ¦Á-hederin-induced contraction of gastric smooth muscle preparations was studied.

lass=""h4"">Materials and methods

The study was carried out on rat isolated stomach corpus and fundus strips, under isotonic conditions. The effect of ¦Á-hederin (100 ¦ÌM) on smooth muscle preparations was measured before and after the treatment with verapamil during the incubation in modified Krebs-Henseleit solution (M K-HS). Besides, the effect of saponin was measured during the incubation of preparation in Ca²⁺-free modified Krebs-Henseleit solution or Ca²⁺-free EGTA-containing modified Krebs-Henseleit solution.

lass=""h4"">Results

The obtained results revealed that the application of verapamil significantly inhibited the reaction evoked by ¦Á-hederin. The incubation of stomach strips in calcium-free modified Krebs-Henseleit solution did not change the force of the observed contraction in comparison to the reaction of the preparations incubated in regular incubation solution (M K-HS). In contrary, the replacement of M K-HS by calcium-free chelator-containing solution inhibited totally the reaction to ¦Á-hederin.

lass=""h4"">Conclusions

The results indicated that ¦Á-hederin-induced contraction results from the influx of calcium which is located in intercellular spaces or bound to the outside of the cell membrane. The Ca²⁺ influx occurs predominantly through voltage-dependent calcium channels of L-type.