AJP - Gastrointestinal and Liver Physiology, Vol 249, Issue 2 228-G235, Copyright © 1985 by American Physiological Society
Characterization of segmental collateral blood flow in the small intestine
G. B. Bulkley, W. A. Womack, J. M. Downey, P. R. Kvietys and D. N. Granger
Collateral blood flow and the pressures and resistances determining that
flow were measured between two adjacent segments of canine jejunum
following acute occlusion of the arterial branch perfusing one of the
segments (the "recipient" segment). Collateral flow was approximately 55%
of control flow in the recipient segment. This flow was provided by an
equal increment in arterial flow to the nonischemic ("donor") segment, such
that pressures, resistances, and flows in the donor segment were not
affected. Virtually all of the total collateral flow was derived from
precapillary channels and was therefore available to the capillary bed of
the recipient segment. Collateral flow was adequate to maintain the
recipient segment in a nonischemic state, as indicated by the absence of a
reactive hyperemia following release of the arterial occlusion. Selective
occlusions of intramural or extramural collateral channels indicate that
about two-thirds of the total collateral flow is derived from the
extramural (marginal) vessels, while the remainder is supplied by
intramural collaterals. For the most part collateral flow between adjacent
segments is determined simply by the pressure gradient between connecting
collateral channels.
