Effects of osthole on isolated guinea pig heart atria
Li, L.; Zhuang, F.E.; Yang, L.; Zhang, C.L.; Zhao, G.S.; Zhao, D.K.
Zhongguo Yao Li Xue Bao 16(3): 251-254
1995
ISSN/ISBN: 0253-9756 PMID: 7660822 Document Number: 448337
AIM: To study the effects of osthole (Ost) on the isolated guinea pig atria and the relationship between Ost effect and Ca-2+. METHODS: Contractions of left atria were induced by electric stimulations. The contractile amplitude of left atria pre- and posttreated with Ost was measured according to the cumulative concentration method, the drug being added at 15 min intervals the pA-2 or pD-2' were calculated. It were measured that the effects of Ost to the positive staircase and to the post-rest potential enhancement. The contractile responses were recorded via an auto-equilibration recording instrument. RESULTS: Ost 10-300 mu-mol cntdot L-1 and Ver 0.1-30 mu-mol cntdot L-1 decreased the contractile force and inhibited the isoprenaline-induced restoration of contractile response in the left atria rendered inexcitable by KCl 25 mmol cntdot L-1. Ost and Ver antagonized the CaCl-2- and isoprenaline-induced positive inotropic response noncompetitively, the pD-2' values to Ost were 4.41 +- 0.13 and 4.90 +- 0.15, to Ver were 6.53 +- 0.22 and 6.91 +- 0.17, respectively. Both of them inhibited the contraction of the left atrium and reversed the frequency-contraction response from positive to negative staircase in the higher dosage (500 and 1 mu-mol cntdot L-1), but they showed only slight inhibitory effect on post-rest potentiation. CONCLUSION: Ost was similar to, but much less potent than Ver in inhibiting the isolated guinea pig atria.