AJP - Gastrointestinal and Liver Physiology, Vol 238, Issue 2 91-G96, Copyright © 1980 by American Physiological Society
Diurnal pH changes in duodenum of conscious dogs
Z. Itoh, R. Honda and I. Aizawa
Continuous measurements of intraduodenal pH changes were made in five
healthy conscious dogs by means of a miniature pH electrode inserted into
the duodenum through a chronically implanted duodenal cannula. Gastric
motor activity was also recorded simultaneously by means of a chronically
implanted force transducer. When dogs were fed once a day with a measured
volume of dog food, it was found that 24-h pH changes in the duodenal
contents could be divided into three major periods: the weak acid period,
the strong acid period, and alkaline period. The weak acid period lasted
for 9.2 +/- 0.43 h after feeding with the duodenal pH ranging from 7.0 to
4.0. The weak acid period was gradually changed to the strong acid period
in which the duodenal pH fluctuated widely from 8.0 to 1.0. This period
lasted for 5.2 +/- 0.26 h. After the strong acid period, pH of the duodenum
abruptly turned alkaline and remained between 7.0 and 8.3 until the next
meal. These three periods of pH change are closely related to those of
three different gastric motor patterns; the digestive, intermediate, and
interdigestive patterns, respectively.
