LONG-TERM MEASUREMENT OF INTRALUMINAL pH OF THE ALIMENTARY TRACT IN CONSCIOUS DOGS

Abstract

Continuous long-term measurement of intraluminal pH of the alimentary tract in conscious dogs is a valuable means to use in the study of the control mechanism in the digestive system and has therefore been tried, mainly in humans, by means of a glass electrode in situ since 1940, however, there were problems involved in the determination of an electrode site and in keeping an electrode in place for long periods.
In the present study, we have developed our own system for measuring pH in situ with a miniature glass electrode inserted through a chronically implanted drainage tube in the alimentary tract. The electrode is a composite type, consisting of a glass membrane (diameter; 2.5mm) and a double glass tube (3×30mm), and a connection to a cable lead was completely waterproofed with silicone. By inserting the electrodes through gastric or duodenal cannulas so that the tips projected 3mm beyond the drainage tube and were in direct contract with the intragastric or intraduodenal contents, the pH of the intraluminal contents could be measured continuously for long periods under stable conditions.
In an attempt to make a quantitative analysis of pH changes, a pH meter was connected to integrators to integrate pH changes above and below 7.0 separately as a product of time and mV. Although such quantitative analysis has not yet been theoretically elucidated, it is useful in determining what changes have occurred over an extended period.
Information obtained by this method will provide us with a key to the releasing mechanism of gastrointestinal hormones and the pathogenesis of duodenal ulcer.