Effect of Levodropropizine on isolated rabbit aorta contracted with phenylephrine and its relationship with calcium

Objective: the aim of this study was to investigate the relationship between calcium (ca^+2) channels and levodropropizine, also to compare the potency of diltiazem and levodropropizine on phenylephrine pre-contracted rabbit aortic rings.methods: 2-3 mm width rings of thoracic aorta were removed and suspended in 25 ml organ baths containing krebs-henseleit solution to reach baseline tension. to investigate contraction inhibiting effect of levodropropizine, ca^+2 free krebs solution was created with na2edta and pre-contraction was induced by 10-5 mol/l phenylephrine. levodropropizine was added in baths and incubated for 15 minutes then cumulative concentration-relaxation curves were obtained increasing the addition of ca^+2 (10-4-10-2 mol/l) by consecutively. results: maximum response occurred with the addition of ca^+2 was inhibited 51.09±5.56% in the presence of levodropropizine (p<0.05). potency of levodropropizine and diltiazem were calculated 95.96±3.12% and 78.28±6.78% respectively (p<0.05). the calculated ic50 values were given as −log ic50 for levodropropizine and diltiazem were 5.095 mol/l and 4.494 mol/l respectively.conclusion: the present in vitro study, it was shown that levodropropizine which is an antitussive drug inhibited extracellular ca^+2 entry by blocking the ca^+2 channels. we think this study would lead further studies which clarify the mechanism of the drug.