AJP - Gastrointestinal and Liver Physiology, Vol 238, Issue 5 434-G439, Copyright © 1980 by American Physiological Society
Effect of glucagon on gastrointestinal blood flow of dogs in hypovolemic shock
J. H. Bond and M. D. Levitt
A microsphere technique was used to study the effect of glucagon on blood
flow to the different tissue layers of the stomach, small bowel, and colon
of the dog in hypovolemic shock. In normal dogs, glucagon caused a twofold
rise in flow to all layers of the stomach and colon, and a threefold
increase to all layers of the small bowel. After administration of
glucagon, a larger fraction of cardiac output was diverted to the gut
microcirculation. In acute hypovolemic shock, intestinal perfusion was
preserved relative to cardiac output inasmuch as cardiac output and gastric
blood flow fell 75% and flow to the small bowel and colon fell by only
about 50%. Glucagon markedly increased the fraction of cardiac output
passing to the gut circulation in hypovolemic shock and, most importantly,
sustained flow to the areas most prone to ischemic necrosis; gastric
mucosa, colonic mucosa, and small intestinal villi. In more prolonged
shock, however, glucagon precipitated fatal cardiovascular collapse unless
part of the lost blood volume first was replaced. Glucagon, therefore,
should not be used in patients in hypovolemic shock without prior
replacement of at least part of the lost blood volume.
