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Quercetin as a novel activator of L‐type Ca 2+ channels in rat tail artery smooth muscle cells
Author(s) -
Saponara Simona,
Sgaragli Giampietro,
Fusi Fabio
Publication year - 2002
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0704631
Subject(s) - quercetin , chemistry , biophysics , activator (genetics) , stimulation , membrane potential , flavonoid , kinetics , biochemistry , endocrinology , biology , receptor , physics , quantum mechanics , antioxidant
The aim of this study was to investigate the effects of quercetin, a natural polyphenolic flavonoid, on voltage‐dependent Ca 2+ channels of smooth muscle cells freshly isolated from the rat tail artery, using either the conventional or the amphotericin B‐perforated whole‐cell patch‐clamp method. Quercetin increased L‐type Ca 2+ current [I Ca(L) ] in a concentration‐ (pEC 50 =5.09±0.05) and voltage‐dependent manner and shifted the maximum of the current‐voltage relationship by 10 mV in the hyperpolarizing direction, without, however, modifying the threshold and the equilibrium potential for Ca 2+ . Quercetin‐induced I Ca(L) stimulation was reversible upon wash‐out. T‐type Ca 2+ current was not affected by quercetin. Quercetin shifted the voltage dependence of the steady‐state inactivation and activation curves to more negative potentials by about 5.5 and 7.5 mV respectively, in the mid‐potential of the curves as well as increasing the slope of activation. Quercetin slowed both the activation and the deactivation kinetics of the I Ca(L) . The inactivation time course was also slowed but only at voltages higher than 10 mV. Moreover quercetin slowed the rate of recovery from inactivation. These results prove quercetin to be a naturally‐occurring L‐type Ca 2+ channel activator.British Journal of Pharmacology (2002) 135 , 1819–1827; doi: 10.1038/sj.bjp.0704631