Effect of hypoxia on Na^+/Ca^<2+> exchange in isolated cardiac myocyte and its regulatory mechanism

缺氧对离体心肌细胞Na^/Ca^2交换的影响及其调控机制

• 批准号: 04670557
• 负责人: MOCHIZUKI Seibu
• 金额: $ 1.28万
• 依托单位: Jikei University School of Medicine
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04670557/
• 关键词: Na^+; Ca^<2+> exchange; forward mode; reverse mode; hypoxia; myocyte; acidosis; Ca^<2+>; Fura 2; 虚血; Fura2; Na; H交換系; Fura‐2 AM; SBFI; H^+交換系; Ca^2^+交換系; 低酸素

Complex changes in ionic movement through the sarcolemma occur after ischemia or hypoxia, and may be restored or aggravated after reperfusion or reoxygenation. Earliest changes are increases in [Ca^<2+>]_i, H_i^+ and [Na^+]_i, However, the interactions between these ions are not fully understood. In this study, the effect of ischemia or hypoxia on intracellular and extracellular ionic changes particularly Na^+/Ca^<2+> exchange was investigated in both isolated cardiac myocytes and isolated perfused rat hearts.[Ca^<2+>]_i, pH_i and [Na^+]_i were measured using fluorescence indicators, Fura-2, BCECF and SBFI,respectively. We have measured increases in the [Ca^<2+>]_i of isolated cardiac myocytes during Na^+-free (Na^+ substituted by TMA^+) exposures using Fura-2 in normoxic and hypoxic solutions and when varing pH_i and pH_0. Hypoxia was produced either by (1) bubbling solution with N_2 or (2) bubbling with N_2 and adding 2-deoxy-D-glucose. After 5 min of hypoxia, the rate of increase in … More [Ca^<2+>]_i during exposure to Na^+-free solutions decreased significantly when compared with that observed in aerobic condition. When pH_i is acidified by adding and removing NH_4Cl, similar inhibitory effects to those observed during hypoxia are produced.When the isolated hearts were perfused with aerobic and ischemic conditions, [Ca^<2+>]_i increases in a biphasic pattern while pH_i decreases rapidly from 7.2 to 6.8 at 3 min add 6.6 at 10 min after hypoxia starts. [Na^+]_i increases gradually during hypoxia. Both the forward and reverse modes of the Na^+/Ca^<2+> exchanger were markedly inhibited during hypoxia and recovered slowly on reoxygenation. The forward mode of Na/Ca exchange was estimated by transient increase in [Ca^<2+>]_i followed by the decay in [Ca^<2+>]_i induced by addition of caffeine. Na^+ channel blocker partially prevented an increase in [Ca^<2+>]_i during hypoxia. These data collectively indicate the complex spectrum of ionic changes, particularly Na^+/Ca^<2+> exchanger that occur during both ischemia/hypoxia and reperfusion/reoxgenation. These results suggested that the Na^+/Ca^<2+> exchange systems, both forward and reverse mode, were inhibited during hypoxia/ischemia. However, an increase in [Ca^<2+>]_i is likely due to the inhibition of forward mode of Na^+/Ca^<2+> exchange since this exchanger normally represents the major efflux pathway for Ca^<2+> in the heart.pH_i changes during hypoxia have also strong modulatory influence on Na^+/Ca^<2+> exchange. Less

缺血或缺氧后，肌膜离子运动发生复杂变化，再灌注或复氧后可恢复或加重。最早的变化是[Ca^<2+>]_i、H_i^+和[Na^+]_i的增加，但这些离子之间的相互作用尚不完全清楚。在这项研究中，我们在离体心肌细胞和离体灌流的大鼠心脏中研究了缺血或缺氧对细胞内外离子变化，特别是Na^+/Ca^<2+>交换的影响。[Ca用荧光指示剂Fura-2、BCECF和SBFI分别测定[Na^+]_i、pH_i和[Na^+]_i。我们用Fura-2在常氧和低氧溶液中以及在改变pH_i和pH_0时，测量了无Na^+（Na^+被TMA^+取代）暴露时离体心肌细胞[Ca^<2+>]_i的增加。用N_2鼓泡法或N_2鼓泡加2-脱氧-D-葡萄糖法造成缺氧。缺氧5 min后， ...更多信息 [Ca与有氧条件下相比，在无Na^+溶液中暴露时的^<2+>]_i显著降低。在离体心脏缺氧和缺血条件下，[Ca^<2+>]_i呈双相性增加，而pH_i则迅速下降，在缺氧开始后3 min从7.2降至6.8，10 min降至6.6。[Na^+]_i在缺氧时逐渐增加。缺氧时Na^+/Ca^<2+>交换的正向和反向模式均受到明显抑制，复氧后恢复缓慢。Na/Ca交换的正向模式是通过加入咖啡因引起[Ca ^<2 +>]_i的瞬时增加和[Ca^<2+>]_i的衰减来估计的。Na^+通道阻断剂可部分抑制缺氧时[Ca^<2+>] i的升高。这些数据共同表明了离子变化的复杂谱，特别是在缺血/缺氧和再灌注/再氧合期间发生的Na^+/Ca^2+交换。结果提示，缺氧/缺血时，Na^+/Ca^<2+>交换系统的正向和反向均受到抑制。然而，[Ca^2+] i的增加可能是由于Na^+/Ca^2+交换的正向模式受到抑制，因为该交换通常代表心脏中Ca^2+的主要外排途径，缺氧时pH_i的变化对Na^+/Ca^2+交换也有很强的调节作用。少

项目成果

Yazaki Y, Mochizuki, S, edited: "Biochemical and Molecular Mechanisms in Cell Function." Kluwer Academic Publishers, 220 (1993)

Yazaki Y、Mochizuki, S 编辑：“细胞功能中的生化和分子机制”。

Yazaki Y,Mochizuki S,edited.: Molecular Mechanisms in Cell Function.Kluwer Academic Biochemical and Publishers, (1993)

Yazaki Y，Mochizuki S，编辑：细胞功能中的分子机制。Kluwer 学术生物化学和出版社，（1993）

Mochizuki,S.et al.: "Ischemia‐reperfusion arrhythmias and lipids:Effect of human high‐and low‐density lipoproteins on reperfusion arrythmias." Cardiovascular Drugs and Therapy. 5. 269-276 (1991)

Mochizuki, S. 等人：“缺血再灌注心律失常和脂质：人类高密度脂蛋白和低密度脂蛋白对再灌注心律失常的影响。”5. 269-276 (1991)。

Mochizuki S., et al: "Ischemia-reperfusion arrhythmias and lipids:Effect of human high- and low-density lipoproteins on reperfusion arrhythmias." Cardiovascular Drugs & Therapy. 5. 269-267 (1991)

Mochizuki S.等人：“缺血再灌注心律失常和脂质：人类高密度脂蛋白和低密度脂蛋白对再灌注心律失常的影响。”

Mochizuki S, et al: "Attenuation of susceptibility to ischemia/reperfusion in isolated, substrate-free perfused heart from diabetic rats." The Adapted Heart.ed by Nagano M, Takeda N, Dhalla S Raven Press N. Y.423-429 (1994)

Mochizuki S 等人：“糖尿病大鼠离体、无基质灌注心脏对缺血/再灌注的敏感性减弱。”