AJP - Gastrointestinal and Liver Physiology, Vol 250, Issue 2 227-G235, Copyright © 1986 by American Physiological Society
Contraction pattern of opossum gallbladder during fasting and after feeding
I. Takahashi, M. K. Kern, W. J. Dodds, W. J. Hogan, S. K. Sarna, K. H. Soergel and Z. Itoh
Our major aims in this study were to determine in unanesthetized opossums
the gallbladder volume, pressure, and tone during fasting as well as after
feeding, model the kinetics of changes in gallbladder volume, and correlate
gallbladder contractility with concurrent spike burst activity in the upper
gastrointestinal tract and sphincter of Oddi (SO). In 10 animals, we
implanted electrodes on the gastric antrum, duodenum, SO, and jejunum. An
indwelling catheter monitored gallbladder pressure and volume. In two
animals, a force transducer sutured to the gallbladder wall monitored
gallbladder tone. In each animal, fasting migrating myoelectric complexes
(MMCs) were recorded in the stomach and small bowel. Cyclic changes in SO
spike bursts occurred in synchrony with the MMCs. During fasting,
gallbladder pressure, tone, and volume showed cyclic variations. During the
second half of the duodenal MMC cycle, the gallbladder exhibited phasic as
well as tonic contractions associated with net gallbladder emptying,
whereas during the first half of the cycle the gallbladder relaxed and
refilled. Minimal gallbladder volume during the MMC cycle averaged 4.8 +/-
0.7 (SE) ml compared with a maximal volume of 7.0 +/- 0.9 ml. Decreases in
gallbladder volume occurred as an exponential function, whereas increases
in gallbladder were linear. After feeding, the gallbladder underwent a
sustained tonic contraction, without superimposed phasic contractions.
Decreases in gallbladder volume occurred exponentially to a residual volume
of 2.0 +/- 0.5 ml. Net postprandial gallbladder emptying was maximal by 40
min; then the volume remained unchanged for 2-3 h.(ABSTRACT TRUNCATED AT
250 WORDS)
