在正常、缺钠及肾上腺切除大鼠体内结肠钾转运研究中使用微型盖革-弥勒计数管和全身计数器。

Use of a miniature GM counter and a whole body counter in the study of potassium transport by the colon of normal, sodium-depleted and adrenalectomized rats in vivo.

作者信息

Barnaby C F, Edmonds C J

出版信息

J Physiol. 1969 Dec;205(3):647-65. doi: 10.1113/jphysiol.1969.sp008988.

DOI:10.1113/jphysiol.1969.sp008988

PMID:5361293

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1348574/

Abstract

A method is described employing a whole-body counter and a miniature GM counter placed within the lumen of the gut which can be used to study the absorption rates and kinetics of labelled substances in the mucosal epithelium in vivo. The method was applied to the study of K transport by the mucosa of the descending colon of normal, Na-depleted and adrenalectomized rats.2. The K influx rate was linearly related to luminal [K] over the range 5-80 mM. NaCN in the lumen produced a fall of electrical potential difference (p.d.) and of K secretion rate but did not reduce K influx rate. The findings were consistent with passive K influx.3. The mucosal (42)K content reached a steady value after 60-90 min of exposure to (42)K in the lumen. The value was similar in normal and adrenalectomized rats but was greater in Na-depleted rats.4. After replacement of luminal solution by a non-radioactive solution the fall of mucosal (42)K content could be described, in the majority, by a curve having two exponential components with half-times of 8-10 and 65-106 min. Approximately half of the (42)K outflow passed to the lumen. The rate constants were similar in all groups of rats.5. The results analysed on the basis of representing the mucosal K as in two compartments, indicated that the observed absorption rate could not be accounted for by transport through these compartments alone and that most of the (42)K crossed the mucosa by a fast pathway not detectable by the miniature GM counter. Most of the mucosal K was relatively inaccessible from the lumen.6. Na depletion raised the transmucosal p.d., increased the K secretion rate and appeared to increase K permeability of the mucosa but the kinetics were unaltered. Accumulation of (42)K in the mucosa was greater, suggesting that the permeability of the luminal face had increased. Adrenalectomy produced only one change, namely a reduction of K secretion rate.

摘要

本文描述了一种方法，该方法使用全身计数器和置于肠道腔内的微型盖革-弥勒计数器，可用于研究体内标记物质在黏膜上皮中的吸收速率和动力学。该方法应用于正常、缺钠和肾上腺切除大鼠降结肠黏膜钾转运的研究。
在5 - 80 mM范围内，钾流入速率与管腔内[K]呈线性关系。管腔内的氰化钠使电位差（p.d.）和钾分泌速率下降，但未降低钾流入速率。这些发现与钾的被动流入一致。
在管腔内暴露于（42）K 60 - 90分钟后，黏膜（42）K含量达到稳定值。正常和肾上腺切除大鼠的值相似，但缺钠大鼠的值更高。
用非放射性溶液替换管腔溶液后，黏膜（42）K含量的下降在大多数情况下可用一条具有两个指数成分的曲线来描述，半衰期分别为8 - 10分钟和65 - 106分钟。大约一半的（42）K流出进入管腔。所有大鼠组的速率常数相似。
根据将黏膜钾表示为两个隔室的分析结果表明，观察到的吸收速率不能仅通过这些隔室的转运来解释，并且大多数（42）K通过微型盖革-弥勒计数器无法检测到的快速途径穿过黏膜。大多数黏膜钾从管腔相对难以到达。
缺钠提高了跨黏膜p.d.，增加了钾分泌速率，似乎还增加了黏膜的钾通透性，但动力学未改变。黏膜中（42）K的积累更多，表明管腔面的通透性增加。肾上腺切除仅产生了一个变化，即钾分泌速率降低。