Author/Editor		Yang, Shi-Bing; Major, Felix; Tietze, Lutz F; Rupnik, Marjan
Title		Block of delayed-rectifier potassium channels by reduced haloperidol and related compounds in mouse cortical neurons
Type		članek
Source		J Pharmacol Exp Ther
Vol. and No.		Letnik 315, št. 1
Publication year		2005
Volume		str. 352-62
Language		eng
Abstract		Haloperidol is known as an antagonist of dopamine D2 receptors. However, it also blocks a variety of ion channels at concentrations above the therapeutic range. Reduced haloperidol (R-haloperidol), one of the main metabolites of haloperidol, has been reported to accumulate in certain tissues, particularly in brain cortex, and it may produce the pharmacological effects associated with haloperidol treatment. In this study, we assessed the effect of R-haloperidol and other related compounds on native delayed-rectifier potassium channels (KDR) in mouse cortical neurons by using the whole-cell patch-clamp technique. Although R-haloperidol has much lower affinity to D2 receptors than haloperidol, the IC50 of R-haloperidol to block KDR currents was 4.4 uM, similar to its parent compound. The binding site of R-haloperidol is on the cytoplasmic side of the channel because its quaternary derivative preferentially inhibited the currents from intracellular side. 4-Chlorophenyl-4-hydroxypiperidine (4C4HP) is the active fragment of haloperidol because other compounds containing this moiety, including L-741, 626 (3-[4-(4-chlorophenyl)-4-hydroxypiperidinL-yl]-methyl-1H-indole) and loperamide, also blocked KDR channels. The potency of the 4C4HP fragment positively correlated with the hydrophobicity index (clogP) of the compounds tested. We conclude that R-haloperidol is a KDR channel blocker, although it does not interfere with the normal channel function at a clinically relevant concentration.
Descriptors		HALOPERIDOL POTASSIUM CHANNELS CEREBRAL CORTEX PATCH-CLAMP TECHNIQUES MICE, INBRED C57BL