Maltby B, Lemon G J, Bassingthwaighte J B, Kelly P J
Am J Physiol. 1982 Apr;242(4):H705-12. doi: 10.1152/ajpheart.1982.242.4.H705.
The kinetics of exchange of strontium (85Sr) and potassium (42K) were studied in the mid-tibial cortical bone of 37 adult dogs. After injection of these two tracer cations and tracer-labeled albumin into the tibial nutrient artery, two types of observations were made: 1) collection of sequential venous samples to provide the outflow indicator-dilution curves and to calculate the extraction and retention at early times; and 2) detection of energy-selected gamma emissions via a detector over the tibia to give the time course of content of 42K and 85Sr in the tibia. Extractions of K+ and Sr2+ were 50 and 60% during a single transcapillary passage. More Sr2+ than K+ was retained in the first minutes. Their rates of washout over a 3-h period were similar. The interpretation is that the rate of uptake at extravascular sites is faster for Sr2+ than for K+, as is the rate of release, and that the extravascular volume of distribution for Sr2+ (adsorption sites in the interstitium or on bone) is much larger than that for K+ (intracellular).
在37只成年犬的胫骨中段皮质骨中研究了锶（85Sr）和钾（42K）的交换动力学。将这两种示踪阳离子和示踪标记白蛋白注入胫骨滋养动脉后，进行了两种类型的观察：1）收集连续的静脉样本以提供流出指示剂稀释曲线，并计算早期的提取率和保留率；2）通过胫骨上方的探测器检测能量选择的γ发射，以给出胫骨中42K和85Sr含量的时间进程。在单次跨毛细血管通过期间，K+和Sr2+的提取率分别为50%和60%。在最初几分钟内，保留的Sr2+比K+多。它们在3小时内的洗脱速率相似。解释是，Sr2+在血管外部位的摄取速率比K+快，释放速率也是如此，并且Sr2+的血管外分布容积（间质或骨上的吸附位点）比K+（细胞内）大得多。
