Antispasmodic and bronchorelaxant activities of Salsola imbricata are mediated through dual Ca(+2) antagonistic and β-adrenergic agonistic effects

Context:Salsola imbricata Forssk. (Chenopodiaceae) has folkloric repute for the treatment of various gastrointestinal and respiratory ailments. Objective: The present study investigates spasmolytic and bronchorelaxant effects of S. imbricata. Materials and methods: The crude aqueous-ethanol extract of the aerial parts of S. imbricata and its fractions, in cumulative concentrations (0.01–10 mg/mL), were tested on contractions of isolated rabbit jejunum and tracheal preparations. Furthermore, concentration response curves (CRCs) of Ca(+2) and carbachol were constructed in the absence and presence of the extract. Standard organ bath methods were used. Results: The crude extract relaxed spontaneous, K(+ )(80 mM) and carbachol (1 μM)-induced contractions in jejunum preparations with respective EC(50) values of 0.40 (0.35–0.46), 0.69 (0.60–0.79) and 0.66 (0.57–0.75) mg/mL. It shifted Ca(+2) CRCs rightward in nonparallel manner. In isolated tracheal preparations, the crude extract caused relaxation of K(+ )(80 mM) and carbachol (1 μM)-induced contractions with EC(50) values of 0.86 (0.75–0.98) and 0.74 (0.66–0.84) mg/mL, respectively. It displaced carbachol CRCs rightward with suppression of maximal response. In both tissues, pretreatment with propranolol (1 μM) caused rightward shift in inhibitory CRCs of the extract against carbachol-induced contractions. The ethyl acetate fraction was found more potent in relaxing smooth muscle contractions than the parent extract and its aqueous fraction. Discussion and conclusion: The results suggest that the spasmolytic and bronchorelaxant activities of S. imbricata are related to Ca(+2) antagonistic and β-adrenergic agonistic effects, thus justifying some of the traditional uses of the plant.