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Effect of Alpha-Allocryptopine on Transient Outward Potassium Current in Rabbit Ventricular Myocytes

Effect of Alpha-Allocryptopine on Transient Outward Potassium Current in Rabbit Ventricular Myocytes

Y Li, S Wang, Y Liu, Z Li, X Yang, H Wang, Y Wen, Y Chen

Cardiology. 2008;111(4):229-36.

PMID: 18434730

Abstract:

Objective:
To investigate the mechanism of alpha-allocryptopine-induced inhibition of the transient outward potassium current (I(to)) in rabbit left-ventricular myocytes.
Methods:
We used the whole-cell patch-clamp technique to record the I(to) in the myocytes, which were isolated from the rabbit left ventricle by a Langendorff-perfusion device.
Results:
Allocryptopine decreased the amplitude and the density of the I(to) in a concentration-dependent (range from 1 to 100 microM with an IC(50) value of 37 +/- 8 microM) and frequency- or use-independent manner. At a test potential of +50 mV, the peak current density of I(to) was decreased from 21.56 +/- 3.24 to 13.37 +/- 2.86 pA/pF by 30 microM allocryptopine. The fast time constant of I(to) inactivation was reduced from 9.8 +/- 1.8 to 5.7 +/- 0.7 ms and the slow time constant of I(to) was reduced from 50.8 +/- 9.0 to 32.2 +/- 12.7 ms by 30 microM allocryptopine. The inactivated curve slope was changed from -19.2 +/- 7.1 to -7.5 +/- 0.6 mV, while the half-activated voltage and activated curve slope and half-inactivated voltage values were not affected by allocryptopine. Transmural heterogeneity of the I(to) was decreased in the presence of allocryptopine. At a test potential of +50 mV, the densities of I(to) were reduced by 28.6% (epimyocardium), 50.3% (mid-myocardium) and 20.1% (endocardium) after exposure to 30 microM allocryptopine.Transmural dispersion of the I(to) was reduced from 11.2 +/- 1.2 to 4.7 +/- 0.6 pA/pF by 30 microM allocryptopine.
Conclusion:
Allocryptopine produced a blocking effect on the I(to) in cardiac myocytes, which may be an important mechanism in its antiarrhythmic effect.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP485916	α-Allocryptopine		485-91-6	Price

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