AJP - Gastrointestinal and Liver Physiology, Vol 242, Issue 1 65-G75, Copyright © 1982 by American Physiological Society
Intestinal filtration-secretion due to increased intraluminal pressure in rabbits
E. A. Swabb, R. A. Hynes, W. G. Marnane, J. S. McNeil, R. A. Decker, Y. H. Tai and M. Donowitz
The mechanism of changes in small intestinal transport due to acutely
increased intraluminal hydrostatic pressure (IHP) was investigated in
detail using perfused in vivo rabbit intestinal segments. IHP affected
passive transport in vivo by increasing effective mucosal surface area in
the small intestine (indicated by 3HOH transport and tissue architectural
changes) and increasing small intestinal permeability (indicated by a
proportionately greater increase in mannitol than erythritol secretory
clearance). IHP did not alter ileal blood flow rate measured by radioactive
microspheres, despite grossly evident venous dilatation, or active
intestinal transport in the ileum as measured by a) in vitro ion transport
in the absence of elevated hydrostatic pressure, b) mucosal adenylate
cyclase or Na-K-ATPase activities, and c) glucose-stimulated water and
electrolyte absorption. Acutely increased IHP appears to influence the
hydrodynamics of the mucosal microcirculation in the rabbit ileum to
produce a driving force for passive filtration-secretion, which is
associated with and possibly augmented by increased tissue permeability and
effective surface area.
