Genistein elicits biphasic effects on L-type Ca2+ current in feline atrial myocytes.
Genistein elicits biphasic effects on L-type Ca2+ current in feline atrial myocytes.
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金雀异黄素对猫心房肌细胞中的 L 型 Ca2 电流产生双相效应。
DOI：
10.1152/ajpheart.1998.275.1.h204
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Lipsius,SL
中科院分区：
文献类型：
--
作者：
Wang,YG;Lipsius,SL
采用穿孔膜片记录法研究了酪氨酸蛋白激酶（PTK）抑制剂染料木黄酮（Gen）对猫心房肌细胞L型钙电流（伊卡，L）的影响。Gen（50 μM）引起ICa，L的双相变化：ICa，L的初始抑制（-55 ± 4%;第1相），随后是二次刺激（34 ± 9%;第2相）。撤除Gen引起ICa，L进一步增强（152 ± 19%; 3期），高于对照组（n= 46）。与对照组相比，1相抑制和3相增强与Gen浓度成正比，2相刺激呈双相浓度依赖性变化。当用破裂膜片记录法透析细胞时，Gen仅引起ICa，L的抑制; 2相和3相消失。蛋白酪氨酸磷酸酶抑制剂钒酸盐（1 mM）可消除Gen对ICa，L.大豆黄酮（50 μM）是Gen的一种弱活性类似物，对ICa，L无明显影响，撤除大豆黄酮也不能增强ICa，L。在少数细胞中，Gen引起了显著的对ICa，L的钒酸敏感的刺激，而对ICa，L没有任何显著的抑制作用。Gen诱导的ICa，L变化不受100 μM 1，2-bis（2-氨基苯氧基）乙烷-N，N，N′，N′-四乙酸（BAPTA）-乙酰氧基甲酯（AM）或1 μM ryanodine，改变细胞内Ca 2+的试剂; 4 μM H-89或50 μM腺苷3′，5 ′-单硫代磷酸酯的Rp非对映体1 μM钙磷抑制素C或2 μM白屈菜红碱，蛋白激酶C（PKC）抑制剂;或100 μ MNG-单甲基-L-精氨酸（l-NMMA），一氧化氮（NO）合酶抑制剂。我们的结论是，在猫心房肌细胞中，Gen通过膜结合的PTKs作用于ICa，L，并通过胞浆PTKs刺激ICa，L。Gen诱导的ICa、L的变化与细胞内Ca ~（2+）的变化或与PKA、PKC或NO信号通路的次级相互作用无关。这些结果表明，在心房肌细胞ICa，Lis由两个独立的和竞争的PTK信号机制。
A perforated patch recording method was used to determine the effects of genistein (Gen), a protein tyrosine kinase (PTK) inhibitor, on basal L-type Ca2+current (ICa,L) in feline atrial myocytes. Gen (50 μM) elicited biphasic changes inICa,L: an initial inhibition (−55 ± 4%;phase 1) followed by a secondary stimulation (34 ± 9%;phase 2) ofICa,L. Withdrawal of Gen elicited a further potentiation ofICa,L(152 ± 19%;phase 3) above control (n= 46). In general,phase 1inhibition andphase 3potentiation varied directly with Gen concentration, andphase 2stimulation exhibited biphasic concentration-dependent changes compared with control. When cells were dialyzed using a ruptured patch recording method, Gen elicited only inhibition ofICa,L;phases 2and3were abolished. Vanadate (1 mM), an inhibitor of protein tyrosine phosphatase, abolished both Gen-induced inhibition and stimulation ofICa,L. Daidzein (50 μM), a weakly active analog of Gen, exerted no significant effects onICa,L, and withdrawal of daidzein failed to potentiateICa,L. In a few cells, Gen elicited a prominent vanadate-sensitive stimulation ofICa,Lin the absence of any significant inhibition ofICa,L. Gen-induced changes inICa,Lwere unaffected by either 100 μM 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (BAPTA)-acetoxymethyl ester (AM) or 1 μM ryanodine, agents that alter intracellular Ca2+; 4 μM H-89 or 50 μM Rp diastereomer of adenosine 3′,5′-monophosphothioate (RP-cAMPS), inhibitors of protein kinase A (PKA); 0.1 μM calphostin C or 2 μM chelerythrine, inhibitors of protein kinase C (PKC); or 100 μMNG-monomethyl-l-arginine (l-NMMA), an inhibitor of nitric oxide (NO) synthase. We conclude that in feline atrial myocytes, Gen acts via membrane-bound PTKs to inhibitICa,Land via cytosolic PTKs to stimulateICa,L. Gen-induced changes inICa,Lare not related to changes in intracellular Ca2+or to secondary interactions with either PKA, PKC, or NO signaling pathways. These results indicate that in atrial myocytesICa,Lis regulated by two independent and competing PTK signaling mechanisms.