Bronchodilatory effect of Acorus calamus (Linn.) is mediated through multiple pathways.
OBJECTIVE
This study was undertaken to provide a pharmacological basis for traditional use of Acorus calamus in airways disorders.


METHODS
Isolated guinea-pig trachea and atria were suspended in organ baths bubbled with carbogen and mechanisms were found using different parameters.


RESULTS
In isolated guinea-pig tracheal segments, crude extract of Acorus calamus was more effective than carbachol in causing relaxation of high K(+) (80 mM) precontractions, similar to verapamil, suggesting blockade of calcium channels. The n-hexane fraction was equipotent against both precontractions, similar to papaverine, while ethylacetate fraction was more potent against carbachol precontractions but had a negligible dilator effect against K(+), similar to atropine and or rolipram. Pretreatment of tracheal preparations with n-hexane or ethylacetate fractions potentiated isoprenaline-induced inhibitory concentration-response curves, similar to papaverine or rolipram. Pretreatment of tracheal preparations with ethylacetate fraction caused a rightward parallel shift in carbachol response curve at lower concentration (0.003 mg/mL) similar to atropine and a non-parallel shift at higher concentrations (0.01 mg/mL), with reduction of maximum response, similar to rolipram. In isolated guinea-pig atrial preparations, crude extracts, its fractions and papaverine inhibited force and rate of contractions at higher concentrations than the smooth muscle while verapamil was equipotent.


CONCLUSIONS
These data indicate the presence of unique combination of airways relaxant constituents in crude extract of Acorus calamus, a papaverine-like dual inhibitor of calcium channels and phosphodiesterase in n-hexane fraction and a novel combination of anticholinergic, rolipram-like phosphodiesterase4 inhibitor in ethylacetate fraction and associated cardiac depressant effect, provide a pharmacological basis for traditional use of Acorus calamus in disorders of airways.
Shah
Abdul Jabbar
AJ
Department of Biological and Biomedical Sciences, Aga Khan University Medical College, Karachi, Pakistan.
Gilani
Anwarul-Hassan
AH
D029023:Acorus; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001993:Bronchodilator Agents / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002217:Carbachol / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D010208:Papaverine / Q000494:pharmacology; D058988:Phosphodiesterase 4 Inhibitors / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D011188:Potassium; D027343:Rhizome; D020889:Rolipram / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects; D014700:Verapamil / Q000494:pharmacology
D001993:Bronchodilator Agents; D002121:Calcium Channel Blockers; D058988:Phosphodiesterase 4 Inhibitors; D010936:Plant Extracts; D001285:Atropine; D002217:Carbachol; D014700:Verapamil; D010208:Papaverine; D020889:Rolipram; D007545:Isoproterenol; D011188:Potassium