A selective T-type Ca2+ channel blocker R(−) efonidipine

MC Shin, CJ Kim, BI Min, S Ogawa, E Tanaka… - Naunyn-Schmiedeberg's …, 2008 - Springer
MC Shin, CJ Kim, BI Min, S Ogawa, E Tanaka, N Akaike
Naunyn-Schmiedeberg's archives of pharmacology, 2008Springer
Abstract Recently, novel compound R (−) efonidipine was reported to selectively block low-
voltage-activated (LVA or T-type) Ca 2+ channels in peripheral organs. We examined how R
(−) efonidipine acts on T-type and high-voltage-activated (HVA) Ca 2+ channels in
mammalian central nervous system (CNS) neurons. Furthermore, we compared the effects
of R (−) efonidipine with those of flunarizine and mibefradil on both T-type and HVA Ca 2+
channels in rat hippocampal CA1 neurons by using the nystatin perforated-patch clamp …
Abstract
Recently, novel compound R(−) efonidipine was reported to selectively block low-voltage-activated (LVA or T-type) Ca2+ channels in peripheral organs. We examined how R(−) efonidipine acts on T-type and high-voltage-activated (HVA) Ca2+ channels in mammalian central nervous system (CNS) neurons. Furthermore, we compared the effects of R(−) efonidipine with those of flunarizine and mibefradil on both T-type and HVA Ca2+ channels in rat hippocampal CA1 neurons by using the nystatin perforated-patch clamp technique. Flunarizine and mibefradil nonselectively inhibited both T-type and HVA Ca2+ channels, though the dose-dependent blocking potency of flunarizine on T-type Ca2+ channels was slightly stronger than that of mibefradil. In contrast, R(−) efonidipine inhibited only T-type Ca2+ channels and did not show any effect on HVA Ca2+ channels. The inhibitory actions of R(−) efonidipine or flunarizine were similar on both Ba2+ and Ca2+ current components passing through T-type Ca2+ channels. In addition, flunarizine but not R(−) efonidipine inhibited voltage-dependent Na+ channels and Ca2+-activated K+ channels. Thus, it appears that R(−) efonidipine is a selective blocker for T-type Ca2+ channels. It could be used as a pharmacological tool in future studies on T-type Ca2+ channels.
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