AJP - Gastrointestinal and Liver Physiology, Vol 251, Issue 1 19-G24, Copyright © 1986 by American Physiological Society
Intestinal blood flow and O2 uptake during hypoxemia in the newborn piglet
P. T. Nowicki, N. B. Hansen, J. R. Hayes, J. A. Menke and R. R. Miller
Previous work has indicated that the neonatal intestinal circulation
responds to hypoxemia with vasoconstriction and subsequent intestinal
ischemia. This work was carried out in newborn lambs, a ruminant species,
and may not be representative of all newborns. Therefore, we measured
intestinal blood flow, vascular resistance, tissue O2 uptake, and cardiac
output during normoxemia and varying degrees of hypoxemia in newborn
piglets, a nonruminant species. Hypoxemia was induced by adding N2 gas to
the inspired gas mixture, and measurements were obtained over a wide range
of arterial O2 contents (2.2-15.6 ml O2 X dl-1). Intestinal blood flow
increased in response to moderate hypoxemia and decreased in response to
severe hypoxemia. The changes in intestinal blood flow were primarily due
to change in intestinal vascular resistance, not cardiac output. Intestinal
O2 was independent of arterial O2 content until the latter decreased below
approximately 6.5 ml O2 X dl-1. These data indicate that the response of
the neonatal intestinal circulation to hypoxemia is species specific and
that the nonruminant neonatal intestine is capable of vasodilation in
response to moderate hypoxemia.
