Fisher R S, Sher D J, Donahue D, Knight L C, Maurer A, Urbain J L, Krevsky B
Department of Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
Am J Gastroenterol. 1997 Feb;92(2):263-70.
Accurate measurement of intragastric acidity has both clinical and investigational importance in studying gastric pathophysiology.
The aims of this study were fourfold: (1) to investigate whether regional differences in intragastric acidity exist; (2) to determine intragastric acidity after a standard antacid was administered in both the fasting and fed states; (3) to monitor gastric emptying of and anatomic distribution of radiolabeled antacid during fasting and postprandial periods; and (4) to determine whether the regional effects of ingested antacid correlated with the anatomic distribution of the antacid.
Eight normal male volunteers were studied after fluoroscopically guided nasogastric placement of a tube assembly containing four pH electrodes, with one electrode in each quartile of the stomach. Simultaneous pH readings were made from the four electrodes while fasting, after administration of fasting antacid (30 ml, 79 mEq buffering capacity), postprandially, and after postprandial antacid ingestion. All subjects repeated the protocol on a separate day, five of them using radiolabeled antacid. Gastric emptying and gastric distribution over time of radiolabeled antacid were determined for comparison to regional intragastric acidity.
Intragastric acidity varied regionally over time in response to meals and to fasting and postprandial antacid. In the fasting state, intragastric acidity returned to baseline after antacid ingestion in a proximal to distal (cardia to antrum) sequence, while postprandial antacid resulted in a return to baseline acidity in a distal to proximal (antrum to cardia) sequence. Radiolabeled antacid distribution paralleled intragastric pH and hydrogen ion concentration in the fasting state, with 82% of the antacid localizing in the distal half of the stomach within the first minute after antacid ingestion. Postprandially, the greatest initial and most prolonged antacid buffering effect occurred proximally, correlating with the presence of radiolabeled antacid. Postprandial antacid remained in the stomach for a longer time (T1/2 = 93.1 +/- 23.4 min) compared with fasting antacid (T1/2 = 23.6 +/- 11.1 min).
Measurement of acidity in the four quartiles of the stomach demonstrated regional variation in response to both food and a standard antacid. A single pH electrode does not detect regional intragastric pH differences.
准确测量胃内酸度在研究胃病理生理学方面具有临床和研究意义。
本研究的目的有四个：（1）研究胃内酸度是否存在区域差异；（2）确定在空腹和进食状态下给予标准抗酸剂后的胃内酸度；（3）监测空腹和餐后期间放射性标记抗酸剂的胃排空和解剖分布；（4）确定摄入抗酸剂的区域效应是否与抗酸剂的解剖分布相关。
对8名正常男性志愿者进行研究，在荧光透视引导下经鼻胃放置一个包含四个pH电极的管组件，胃的每个四分位区域放置一个电极。在空腹、给予空腹抗酸剂（30毫升，缓冲能力79毫当量）后、餐后以及餐后摄入抗酸剂后，同时从四个电极读取pH值。所有受试者在另一天重复该方案，其中5人使用放射性标记抗酸剂。测定放射性标记抗酸剂随时间的胃排空和胃分布，以与胃内区域酸度进行比较。
胃内酸度随时间在区域上有所变化，这取决于进餐以及空腹和餐后抗酸剂的情况。在空腹状态下，摄入抗酸剂后胃内酸度按近端到远端（贲门到胃窦）的顺序恢复到基线，而餐后抗酸剂则按远端到近端（胃窦到贲门）的顺序使酸度恢复到基线。在空腹状态下，放射性标记抗酸剂的分布与胃内pH值和氢离子浓度平行，抗酸剂摄入后第一分钟内82%的抗酸剂位于胃的远端半部。餐后，最初最大且持续时间最长的抗酸剂缓冲作用发生在近端，与放射性标记抗酸剂的存在相关。与空腹抗酸剂（半衰期=23.6±11.1分钟）相比，餐后抗酸剂在胃内停留的时间更长（半衰期=93.1±23.4分钟）。
对胃的四个四分位区域的酸度测量显示，对食物和标准抗酸剂的反应存在区域差异。单个pH电极无法检测到胃内区域pH值差异。
