Flatman P W
J Physiol. 1983 Aug;341:545-57. doi: 10.1113/jphysiol.1983.sp014823.
Potassium movements into ferret red cells were measured with the tracer 86Rb. Equilibration of 86Rb between medium and cells could be resolved into two components. 70-90% occurred rapidly with a rate constant of between 3.5-5.5 h-1. The remaining 10-30% occurred slowly. The slow movement was equivalent to a potassium influx of about 1.2-2.76 mmol l-1 cell h-1. Potassium influx was inhibited by 80-90% by 0.1 mM-bumetanide (a high-ceiling, loop diuretic). This suggests that the sodium-potassium co-transport system has a high capacity for carrying potassium (estimated at about 17-35 mmol l-1 cell h-1). After bumetanide (0.1 mM) remaining potassium movements (approximately 0.5 mmol l-1 cell h-1) are at a similar level to that found in red cells from other animals. The sodium pump makes a very small contribution to potassium flux into ferret red cells. Much of this pump activity may be attributed to reticulocytes present in cell samples. Sodium movements across the red cell membrane were measured with 22Na. Sodium equilibrated more slowly than potassium. 60-70% of the sodium influx was inhibited by 0.1 mM-bumetanide, indicating that most sodium influx in ferret red cells is also through the co-transport system. The co-transport system can transport up to 49 mmol sodium l-1 cell h-1 and is half maximally activated by 0.38 mM-potassium in the external medium. In the presence of bumetanide, sodium influx (about 18 mmol l-1 cell h-1) is similar to that of other carnivore red cells. This is about five times greater than that of red cells from non-carnivores. The possibility that there are two populations of ferret red cells with different potassium transport characteristics is discussed.
用示踪剂86Rb测量了雪貂红细胞内钾的转运情况。86Rb在培养基和细胞之间的平衡可分为两个部分。70 - 90%的平衡迅速发生，速率常数在3.5 - 5.5 h-1之间。其余10 - 30%的平衡发生得较慢。缓慢的转运相当于钾流入细胞的速率约为1.2 - 2.76 mmol·l-1·细胞·h-1。0.1 mM布美他尼（一种高效能袢利尿剂）可使钾流入量减少80 - 90%。这表明钠钾协同转运系统运载钾的能力很强（估计约为17 - 35 mmol·l-1·细胞·h-1）。在布美他尼（0.1 mM）作用后，剩余的钾转运量（约0.5 mmol·l-1·细胞·h-1）与其他动物红细胞中的水平相似。钠泵对钾流入雪貂红细胞的贡献非常小。这种泵活性的很大一部分可能归因于细胞样本中存在的网织红细胞。用22Na测量了钠穿过红细胞膜的转运情况。钠达到平衡的速度比钾慢。0.1 mM布美他尼可抑制60 - 70%的钠流入，这表明雪貂红细胞中大部分钠流入也是通过协同转运系统进行的。该协同转运系统每小时每升细胞可转运多达49 mmol钠，外部培养基中0.38 mM钾可使其达到最大激活程度的一半。在布美他尼存在的情况下，钠流入量（约18 mmol·l-1·细胞·h-1）与其他食肉动物红细胞的相似。这大约是非食肉动物红细胞钠流入量的五倍。文中讨论了雪貂红细胞是否存在两种具有不同钾转运特征群体的可能性。
