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The Ca(++)-channel blocker Ro 40-5967 blocks differently T-type and L-type Ca++ channels

The effects of Ro 40-5967, a nondihydropyridine Ca++ channel blocker, on low-voltage activated (T-type) and high-voltage activated (L-type) Ca++ channels were compared. L-type barium currents were measured in Chinese hamster ovary cells stably transfected with the alpha 1 subunit of the class Cb Ca+...

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Bibliographic Details
Main Authors: Mehrke, Gerhard (Author) , Zong, X. G. (Author) , Flockerzi, Veit (Author) , Hofmann, Franz (Author)
Format: Article (Journal)
Language:English
Published: December 1994
In: The journal of pharmacology and experimental therapeutics
Year: 1994, Volume: 271, Issue: 3, Pages: 1483-1488
ISSN:1521-0103
DOI:10.1016/S0022-3565(25)24034-4
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1016/S0022-3565(25)24034-4
Verlag, lizenzpflichtig, Volltext: https://www.sciencedirect.com/science/article/pii/S0022356525240344
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Author Notes:G. Mehrke, X.G Zong, V. Flockerzi, F. Hofmann
Description
Summary:The effects of Ro 40-5967, a nondihydropyridine Ca++ channel blocker, on low-voltage activated (T-type) and high-voltage activated (L-type) Ca++ channels were compared. L-type barium currents were measured in Chinese hamster ovary cells stably transfected with the alpha 1 subunit of the class Cb Ca++ channel. T-type barium currents were investigated in human medullary thyroid carcinoma cells. The Ba++ currents of human medullary thyroid carcinoma cells were transient, activated at a threshold potential of -50 mV with the maximum at -14 +/- 3.2 mV and blocked by micromolar Ni++. The T- and L-type current inactivated with time constants of 33.4 +/- 4.1 and 416 +/- 26 msec at maximum barium currents, respectively. Ro 40-5967 inhibited reversibly the T- and L-type currents with IC50 values of 2.7 and 18.6 microM, respectively. The inhibition of the L-type current was voltage-dependent, whereas that of the T-type current was not. Ro 40-5967 blocked T-type current already at a holding potential of -100 mV. The different types of block, i.e., voltage-dependent vs. tonic block, may contribute to the pharmacological profile of Ro 40-5967 in intact animals.
Item Description:Elektronische Reproduktion der Druck-Ausgabe 31. Januar 2025
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Physical Description:Online Resource
ISSN:1521-0103
DOI:10.1016/S0022-3565(25)24034-4

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