Ikeda U, Briggs G M, Allen P D, Sen L, Medford R M, Smith T W
Department of Medicine, Brigham and Women's Hospital, Boston, MA.
Cardioscience. 1990 Sep;1(3):225-33.
Adult mammalian cardiac myocytes in long-term culture offer advantages over intact heart tissue and freshly isolated ventricular cell preparations for a variety of experimental studies. To characterize this preparation in detail, we have examined the physiological properties of isolated adult rat ventricular cells maintained in culture for 10-14 days. Adult rat myocytes in longterm culture contracted spontaneously, with electrical coupling of adjacent cells, at 1-3 Hz. Most myocytes showed myofibrils with well-developed mitochondria and transverse tubular systems. They showed predominantly the V1 type myosin heavy chain isoform. In standard physiological superfusion media (pH 7.35), the intracellular pH of cultured cells measured with 2',7'-bis-carboxyethyl-carboxyfluorescein (BCECF) was 7.26 +/- 0.03, and was regulated by an amiloride-sensitive Na-H exchanger. The time-averaged free intracellular Ca2+ level of cultured adult rat myocytes measured with fura-2 at an extracellular Ca2+ level of 1 mM was 99.0 +/- 16.8 nM. Ouabain, Bay k 8644 or isoproterenol caused a significant rise in time-averaged intracellular [Ca2+], while the dihydropyridine Ca channel blocker nifedipine induced a decrease in intracellular [Ca2+]. Measurements of contractile state with an optical-video system demonstrated that ouabain. Bay k 8644, isoproterenol, or elevated extracellular [Ca2+] increased the amplitude of cell motion and the rates of both shortening and relaxation, while nifedipine lowered them. Microelectrode impalements indicated a resting potential of -75 +/- 1 mV and an action potential amplitude of 100 +/- 2 mV. Exposure of cultured adult rat cardiocytes to the thyroid hormone triiodothyronine (10 nM) for 48 hours resulted in a 2-fold increase in NaK-ATPase alpha-1 catalytic subunit mRNA accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)
在各种实验研究中，长期培养的成年哺乳动物心肌细胞比完整的心脏组织和新鲜分离的心室细胞制剂具有优势。为了详细表征这种制剂，我们研究了在培养10 - 14天的成年大鼠离体心室细胞的生理特性。长期培养的成年大鼠心肌细胞以1 - 3Hz的频率自发收缩，相邻细胞存在电偶联。大多数心肌细胞显示出具有发育良好的线粒体和横管系统的肌原纤维。它们主要表现为V1型肌球蛋白重链异构体。在标准生理灌注培养基（pH 7.35）中，用2',7'-双羧乙基羧基荧光素（BCECF）测量的培养细胞的细胞内pH值为7.26±0.03，并由氨氯地平敏感的钠氢交换体调节。在细胞外Ca2+水平为1 mM时，用fura-2测量的培养成年大鼠心肌细胞的时间平均游离细胞内Ca2+水平为99.0±16.8 nM。哇巴因、Bay k 8644或异丙肾上腺素导致时间平均细胞内[Ca2+]显著升高，而二氢吡啶类钙通道阻滞剂硝苯地平则导致细胞内[Ca2+]降低。用光学视频系统测量收缩状态表明，哇巴因、Bay k 8644、异丙肾上腺素或细胞外[Ca2+]升高会增加细胞运动幅度以及缩短和松弛速率，而硝苯地平则使其降低。微电极刺入显示静息电位为 - 75±1 mV，动作电位幅度为100±2 mV。将培养的成年大鼠心肌细胞暴露于甲状腺激素三碘甲状腺原氨酸（10 nM）48小时导致NaK - ATPaseα-1催化亚基mRNA积累增加2倍。（摘要截短至250字）
