Solomon T E, Grossman M I, Meyer J H
Am J Physiol. 1978 Nov;235(5):E560-4. doi: 10.1152/ajpendo.1978.235.5.E560.
To test the hypothesis that the permeability of weak acids across the intestinal mucosa affects their ability to stimulate pancreatic bicarbonate output, we compared pancreatic bicarbonate secretion in response to intestinal perfusion with an acid presumed to be permeable to cell membranes, lactic acid (90 daltons), and an acid presumed to be impermeable, acidified bovine serum albumin (about 70,000 daltons). These two substances have similar titration curves from pH 2.00 to pH 4.50. In four conscious dogs with pancreatic fistulas, solutions of these weak acids were perfused at 50 ml/15 min into the intestine at concentrations adjusted to deliver 1, 2, or 4 mmol/15 min of acid titratable to pH 4.50 (threshold pH for bicarbonate stimulation) from an initial pH of 2.00 or 3.50. At both pH 2.00 and 3.50 and at all titratable acid loads, bicarbonate secretory responses to lactic acid and acidified albumin were not significantly different. Equal titratable acid loads of HCl produced much larger secretory responses. The data do not support the hypothesis that permeability of weak acids is a factor, but confirm the observation that weak acids are less potent than strong acids in stimulating pancreatic bicarbonate secretion.
为了验证弱酸跨肠黏膜的通透性会影响其刺激胰腺分泌碳酸氢盐能力这一假说，我们比较了在向肠道灌注两种酸后胰腺碳酸氢盐的分泌情况，一种是被认为可透过细胞膜的酸——乳酸（90道尔顿），另一种是被认为不可透过细胞膜的酸——酸化牛血清白蛋白（约70,000道尔顿）。这两种物质在pH值从2.00到4.50范围内具有相似的滴定曲线。在四只患有胰瘘的清醒犬中，将这些弱酸溶液以50毫升/15分钟的速度灌注到肠道中，其浓度经过调整，以便从初始pH值2.00或3.50开始，在15分钟内输送1、2或4毫摩尔可滴定至pH值4.50（刺激碳酸氢盐分泌的阈值pH值）的酸。在pH值2.00和3.50时以及所有可滴定酸负荷条件下，乳酸和酸化白蛋白引起的碳酸氢盐分泌反应无显著差异。等量可滴定酸负荷的盐酸产生的分泌反应要大得多。这些数据不支持弱酸通透性是一个影响因素的假说，但证实了弱酸在刺激胰腺碳酸氢盐分泌方面比强酸效力更低这一观察结果。
