AJP - Gastrointestinal and Liver Physiology, Vol 259, Issue 2 314-G320, Copyright © 1990 by American Physiological Society
Changes in tone of canine gallbladder measured by an electronic pneumatic barostat
M. Tanaka, M. G. Sarr, L. J. Miller and J. R. Malagelada
Department of Surgery, Mayo Medical School, Rochester, Minnesota 55905.
We developed an electronic pneumatic barostat to measure changes in
gallbladder muscle tone in vivo independent of biliary flow dynamics. Dogs
were prepared with a gallbladder cannula for insertion of barostat balloon
and an inflatable balloon-occluder around the cystic duct. The barostat was
validated to maintain a constant pressure of 2 +/- 0.4 (SE) mmHg within a
plastic balloon of "infinite" compliance that filled the gallbladder lumen;
changes in balloon volume reflected changes in wall tone because
intraluminal pressure was kept constant. Gallbladder tone, as measured by
the barostat balloon volume, varied cyclically with the duodenal migrating
motor complex and decreased by 28 +/- 8% (P less than 0.05) at the time of
phase III in the stomach and duodenum. Superimposed rapid changes in
barostat volume occurred during phase III. The barostat response to motilin
mimicked events during spontaneous phase III; in contrast, the response to
cholecystokinin octapeptide (CCK-OP) was greater (volume decrease = 53 +/-
12%) and no phasic changes occurred. Two distinct patterns of gallbladder
contraction were demonstrated: a basal tone increase with superimposed
phasic contractions observed during phase III and after motilin, and a
basal tone increase without phasic activity that occurs after CCK-OP.
