AUTORADIOGRAPHIC DEMONSTRATION OF INHOMOGENEOUS DISTRIBUTION OF SODIUM IN SINGLE OOCYTES OF BUFO-BUFO
AUTORADIOGRAPHIC DEMONSTRATION OF INHOMOGENEOUS DISTRIBUTION OF SODIUM IN SINGLE OOCYTES OF BUFO-BUFO
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DOI：
10.1113/jphysiol.1970.sp009212
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发表时间：
1970-01-01
影响因子：
5.5
通讯作者：
ROGERS, AW
中科院分区：
文献类型：
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作者：
DICK, DAT;FRY, DJ;ROGERS, AW
1. 用22na标记的冷冻细胞放射自显影术已被用于定位卵母细胞中隔离的一部分内部Na，这些Na与外部li交换非常缓慢或根本不交换。用光度法测定核和细胞质中的相对颗粒密度，作为22na在卵母细胞内分布的指示。在测试实验中，在截面边缘19 μm范围内，晶粒密度下降到50%。由于卵母细胞直径大（bbb600 μm），核直径大（> 200 μm），该分辨率足以测定颗粒密度的细胞质/核（C/N）比。在满载22na的卵母细胞中，平均C/N比值为0.92±0.03 （N = 11）。在Li -取代Na - free Ringer溶液中交换5小时后，平均C/N比为2.18±0.04 （N = 11）。对照林格氏液交换5小时后，平均C/N比为1.39±0.18 （N = 7）。因此，细胞质中含有一小部分不能与Li交换的22na，而且与Na交换的速度比在细胞核中要慢。由此揭示的内部Na的非Li交换部分似乎在数量上与已经通过钠敏感微电极对22na通量和内部Na活性的研究所证明的相似。
1. Autoradiography of frozen cells labelled with22Na has been used to locate a sequestered fraction of internal Na in the oocyte which exchanges very slowly or not at all with external Li.2. Relative grain density in nucleus and cytoplasm, measured photometrically, was used as an indication of22Na distribution within the oocyte. In test experiments grain density fell to 50% within 19 μm of the edge of the section. Owing to the large diameter of the oocyte (> 600 μm) and its nucleus (> 200 μm), this resolution was adequate to determine cytoplasmic/nuclear (C/N) ratios of grain density.3. In oocytes fully loaded with22Na, the mean C/N ratio was 0·92 ± 0·03 (n= 11). After 5 hr exchange in Li‐substituted Na‐free Ringer solution, the mean C/N ratio was 2·18 ± 0·04 (n= 11). After 5 hr exchange in Ringer solution as a control, the mean C/N ratio was 1·39 ± 0·18 (n= 7). The cytoplasm thus contained a fraction of22Na inexchangeable with Li, and more slowly exchangeable with Na than that in the nucleus.4. The non‐Li‐exchangeable fraction of internal Na thus revealed appeared to be quantitatively similar to that already demonstrated by studies of22Na fluxes and of internal Na activity by means of Na‐sensitive micro‐electrodes.