Summary
Tetrandrine (Tet) 0.32 mmol/1 and verapamil (Ver) 30 μmol/1 inversed positive staircase phenomenon of contraction in left alrium of guinea pig. After the preparation was partially depolarized with K+ 20 mmol/1, such effect of Tet and Ver became much more pronounced. Propranolol could not inverse the positive staircase phenomenon. In addition, after treatment with Tet 0.32 mmol/1 for 20 min the post -rest potentiation of myocardial contraction in the left atrium was depressed by 2.8±0.3 g (P<0.01). The results suggest that the negative inotropism of Tet is related not only to the inhibition of Ca++ influx to the cells, but also to the decrease of the intracellular Ca++ release.
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Gang, W., Bin, C., Xian-gang, Z. et al. Studies on the calcium antagonistic action of tetrandrine: X VI. Effects of tetrandrine on positive staircase phenomenon and post-rest potentiation of contraction of isolated guinea pig left atrium. Journal of Tongji Medical University 8, 198–201 (1988). https://doi.org/10.1007/BF02887890
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DOI: https://doi.org/10.1007/BF02887890