シミズ　タツヤ   Shimizu Tatsuya   清水　達也    所属   医学研究科 医学研究科 (医学部医学科をご参照ください)    職種   教授
論文種別	原著
言語種別	英語
査読の有無	査読なし
表題	Selectivity of felodipine for depolarized ventricular myocytes: a study at the single-cell level.
掲載誌名	正式名：European journal of pharmacology 略　 称：Eur J Pharmacol ISSNコード：(0014-2999)0014-2999(Linking)
掲載区分	国外
巻・号・頁	319(2-3),pp.355-63
著者・共著者	Kohmoto O†, Shimizu T, Sugishita K, Kinugawa K, Takahashi T, Serizawa T
発行年月	1997/01
概要	We studied the effects of felodipine (a second-generation dihydropyridine Ca2+ channel blocker) on excitation-contraction coupling (E-C coupling) in single isolated guinea-pig ventricular myocytes, using the whole-cell perforated patch-clamp technique or the Ca indicator, indo-1. Felodipine inhibited both L-type Ca2+ channel currents (ICa) and cell contractions in a concentration-dependent manner (10 pM to 100 nM) when we used a holding potential of -80 mV or -40 mV. The potency of felodipine was sharply dependent on a holding potential. Namely, use of a more depolarized holding potential markedly increased the potency of felodipine for inhibition of ICa and cell contraction. Next we current-clamped cells and obtained the resting membrane potential of -82 +/- 8 mV. When cells were current-injected at 0.1 Hz, exposure to 10 nM felodipine slightly but significantly diminished the amplitude of cell contractions (7.2 +/- 1.6 to 6.7 +/- 1.7 microns, P < 0.05) within 10 min. When cells were field stimulated, exposure of cells to 10 nM felodipine also slightly diminished the amplitude of cell shortening (5.1 +/- 2.0 to 4.6 +/- 1.9 microns, P < 0.05) and [Ca2+]i transients. We observed clear voltage-dependent blockade of E-C coupling by felodipine in ventricular myocytes. Thus, therapeutic concentrations (1-10 nM) of felodipine could inhibit E-C coupling in depolarized ventricular myocytes, which might simulate an ischemic or failing heart.
DOI	https://doi.org/10.1016/S0014-2999(96)00867-9
PMID	9042611