FLUORESCENT PROPERTIES OF RAT CARDIAC TRABECULAE MICROINJECTED WITH FURA-2 SALT
FLUORESCENT PROPERTIES OF RAT CARDIAC TRABECULAE MICROINJECTED WITH FURA-2 SALT
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DOI：
10.1152/ajpheart.1993.264.4.h1098
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发表时间：
1993-04-01
影响因子：
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通讯作者：
TERKEURS, HEDJ
中科院分区：
文献类型：
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作者：
BACKX, PH;TERKEURS, HEDJ
我们测量了大鼠心脏小梁抽搐时的力、肌节长度和 Ca2+。为了避免与 fura-2/乙酰氧基甲酯 (AM) 相关的困难，使用单个穿刺位点将 fura-2 盐通过离子电渗显微注射到制剂中；这是可能的，因为 fura-2 通过细胞之间的间隙连接扩散。通过使用这种方法，在不同的肌节长度下，抽搐期间 [Ca2+] 瞬变的估计峰值没有统计学差异：肌节长度为 2.15 mm 时为 875 +/- 92 nM，而肌节长度为 1.65 mm 时为 905 +/- 67 nM（平均值 +/- SD，n = 10）。当使用 fura-2/AM 加载小梁时，肌节长度为 2.15 mm 时 [Ca2+] 瞬态的估计峰值为 540 +/- 180 nM（平均值 +/- SD，n = 5）。不同肌节长度处的 Ca2+ 瞬变的时间进程在性质上相似，但在松弛期间观察到小的系统差异。另一方面，随着肌肉长度的增加，抽搐力的持续时间急剧增加。因此，当小梁保持较短的肌肉长度时，力和 Ca2+ 瞬变之间的时间关系类似于细胞缩短和在分离的心肌细胞中测量的 Ca2+ 瞬变之间的关系。在较长的长度下，力和 Ca2+ 瞬变之间的时间关系更接近于使用水母发光蛋白在乳头肌中获得的关系。
We have measured force, sarcomere length, and Ca2+ during twitches in rat cardiac trabeculae. To avoid the difficulties associated with fura-2/acetoxymethyl ester (AM), fura-2 salt was iontophoretically microinjected into the preparation using a single impalement site; this is possible because fura-2 diffuses through the gap junctions between cells. By use of this method, the estimated peak of the [Ca2+] transient during a twitch was not statistically different at different sarcomere lengths: 875 +/- 92 nM at a sarcomere length of 2.15 mum vs. 905 +/- 67 nM at a sarcomere length of 1.65 mum (means +/- SD, n = 10). When trabeculae were loaded using fura-2/AM, the estimated peak of the [Ca2+] transient at a sarcomere length of 2.15 mum was 540 +/- 180 nM (means +/- SD, n = 5). The time course of the Ca2+ transients at different sarcomere lengths is qualitatively similar, but small systematic differences were observed during the relaxation period. On the other hand, the duration of twitch force increases dramatically as the muscle length is increased. As a result, when the trabeculae were held at short muscle lengths,the temporal relationship between force and the Ca2+ transient resembled the relationship between cell shortening and the Ca2+ transient measured in isolated myocytes. At longer lengths the temporal relationship between force and the Ca2+ transient more closely resembles that obtained in papillary muscles using aequorin.