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[Effect of xanthnotoxol on contractility of isolated rabbit ileum]
1Department of Pharmacology, Gannan Medecal College, Ganzhou 341000, Jiangxi, China.
Objective:
To study the effect of Xanthnotoxol on contractility of isolated rabbit ileum and its relationship with Ca2+.
Method:
Routine experimental methods for isolated ileum were adopted.
Result:
Xanthnotoxol (XT) and Verapamil (Ver) inhibited the contraction of isolated rabbit ileum smooth muscle induced by submaximal concentrations of acetylcholine (ACh) and serotonim (5-TH), with a IC50 value (mumol.L-1) of 10.495 +/- 1.521, 0.428 +/- 0.001 and 18.132 +/- 1.627, 0.249 +/- 0.003, respectively. XT and Ver inhibited the contraction induced by Ca2+ after high K+ depolarization and for noncompetitively antagonist CaCl2 cumulative dose-response curve, the pD'2 value was 4.69 +/- 0.03 and 6.35 +/- 0.10, respectively. XT (10 mumol.L-1) and Ver(0.06 mumol.L-1) inhibited the contraction induced by ACh in Ca(2+)-free medium, while XT (100 mumol.L-1) but not Ver(0.6 mumol.L-1) inhibited the extracellar CA(2+)-dependent contraction induced by ACh.
Conclusion:
XT has a calcium-antagonistic effect which was not similar to that of Ver.