Title: Mechanism of cardiac T-type Ca channel blockade by amiloride
Authors: Tytgat, Jan ×
Vereecke, Johan
Carmeliet, Edward #
Issue Date: Sep-1990
Series Title: Journal of Pharmacology and Experimental Therapeutics. vol:254 issue:2 pages:546-51
Abstract: Whole cell clamp experiments were used to study the mechanism of action of amiloride on cardiac T-type Ca channels in guinea pig ventricular myocytes. Two hundred fifty microM amiloride blocked the T-type Ca channel for approximately 50%, whereas this concentration did not suppress the L-type Ca channel. The Kd value for the block of the T-type Ca channel was 233 microM and the Hill coefficient was 1.1. The drug showed a rapid onset of action and a quick wash out with complete reversibility. Amiloride blocked the T-type Ca channel without frequency-dependency, i.e., block was established at the holding potential (-90 mV) without being dependent on activation and inactivation of the channel. Amiloride reduced the amplitude of the T-type Ca current at all potentials without changing steady-state activation and inactivation. Amiloride did not affect the T-type Ca current when the drug was applied intracellularly via the pipette solution. In summary, amiloride blocked the T-type Ca channel in a channel state- and voltage-independent way.
ISSN: 0022-3565
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Toxicology and Pharmacology
Physiology Section (-)
Laboratory of Molecular and Cellular Signaling
Department of Cellular and Molecular Medicine - miscellaneous
× corresponding author
# (joint) last author

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