Studies on the calcium antagonistic action of tetrandrine: XI: Effects of tetrandrine and verapamil on contractility and oxygen consumption in heart muscle

Abstract

The effects of tetrandrine (Tet) and verapamil (Ver) on contractility and oxygen consumption were studied and compared in isolated guinea pig left atrial strips and cat papillary muscles. Both drugs diminished the Ca⁺⁺-dependent contractile force and the oxygen consumption of electrically driven preparations. These effects were antagonized by increasing the extracellular Ca⁺⁺ concentration.

Under the influence of increasing doses of Tet (52–210 μM) and Ver (0.72-2.9 μM) linear reduction of isometric tension and oxygen consumption due to mechanical activity was seen. With Tet 0.21 mM and Ver 2.9 μM the tension development and contractility-dependent oxygen consumption decreased greatly.

The results indicate that Tet, like Ver, is also an effective Ca⁺⁺-antagonist.

Keywords

tetrandrine / iproveratril / O₂-consumption / isometric muscle contraction / papillary muscles of cat / atrial strips of guinea pig / calcium channel blocker

References

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