Hypoxia increases the sensitivity of the L-type Ca2+ current to β-adrenergic receptor stimulation via a C2 region-containing protein kinase C isoform
Hypoxia increases the sensitivity of the L-type Ca2+ current to β-adrenergic receptor stimulation via a C2 region-containing protein kinase C isoform
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DOI：
10.1161/01.res.87.12.1164
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发表时间：
2000-12-08
影响因子：
20.1
通讯作者：
Hool, LC
中科院分区：
文献类型：
--
作者：
Hool, LC
在不存在和存在β-肾上腺素能受体激动剂异丙肾上腺素（Iso）的情况下，检测了缺氧对L-型钙电流（ICa-L）的影响。豚鼠心室肌细胞暴露于单独的缺氧导致可逆的抑制基础ICa-L。当细胞在缺氧条件下暴露于Iso时，Iso激活ICa-L的K-0.5从5.3+/-0.7降至1.6+/-0.1 nmol/L。膜不透性巯基特异性氧化剂5.5 '-二硫代-双（2-硝基苯甲酸）（DTNB）可使缺氧对基础ICa-L的抑制减弱81.3 ± 9.4%，但对增加ICa-L对Iso的敏感性无影响。此外，DTT模拟缺氧对基础ICa-L的影响和对Iso敏感性的增加。鸟苷酸环化酶抑制剂LY-83583或亚甲蓝或NO合酶抑制剂N-G-单甲基-L-精氨酸单乙酸酯对缺氧时Iso对ICa-L的基础抑制或对ICa-L激活的K-0.5的降低均无影响。然而，蛋白激酶C（PKC）抑制剂bisindolylmaleimide I和Go 7874显着减弱增加的ICa-L对Iso的敏感性。更具体地说，当细胞用含C2区的经典PKC亚型的肽抑制剂透析时，反应减弱。PKC β肽抑制剂没有观察到相同的效果。这些结果表明，缺氧通过以下2种不同的机制调节ICa-L：直接抑制基础ICa-L和间接影响通道对β-肾上腺素能受体刺激的敏感性，这是通过经典的PKC亚型介导的。
The effects of hypoxia on the L-type Ca2+ current (ICa-L) in the absence and presence of the beta -adrenergic receptor agonist isoproterenol (Iso) were examined. Exposing guinea Dig ventricular myocytes to hypoxia alone resulted in a reversible inhibition of basal ICa-L. When cells were exposed to Iso in the presence of hypoxia, the K-0.5 for activation of ICa-L by Iso was significantly decreased from 5.3+/-0.7 to 1.6+/-0.1 nmol/L. The membrane-impermeant thiol-specific oxidizing compound 5.5'-dithio-bis(2-nitrobenzoic acid) (DTNB) attenuated the inhibition of basal ICa-L by hypoxia 81.3+/-9.4%, but had no effect on the increase in sensitivity of ICa-L to Iso. In addition, DTT mimicked the effects of hypoxia on basal ICa-L and the increase in sensitivity to Iso. Neither the inhibitors of guanylate cyclase LY-83583 or methylene blue nor the NO synthase inhibitor N-G-monomethyl-L-arginine monoacetate had any effect on the basal inhibition of ICa-L or the decrease in K-0.5 for activation of ICa-L by Iso during hypoxia. However, the protein kinase C (PKC) inhibitors bisindolylmaleimide I and Go 7874 significantly attenuated the increase in sensitivity of ICa-L to Iso. More specifically, the response was attenuated when cells were dialyzed with a peptide inhibitor of the C2 region-containing classical PKC isoforms. The same effect was not observed with the PKC epsilon peptide inhibitor. These results suggest that hypoxia regulates ICa-L through the following 2 distinct mechanisms: direct inhibition of basal ICa-L and an indirect effect on the sensitivity of the channel to beta -adrenergic receptor stimulation that is mediated through a classical PKC isoform.