Dynamics of arterial and portal venous flow interactions in
perfused rat liver: an intravital microscopic study .
Sherman, Igor A., John A. Dlugosz, Ford Barker, Farhad M. Sadeghi, and
K. Sandy Pang.
Aaron M. Rappaport Microcirculation Laboratory, University of
Toronto, Faculty of Pharmacy, Toronto, Ontario, Canada M5S 2S2,
Institute of Biomedical Engineering, University of Toronto, Toronto,
Ontario, Canada M5S 1A8, Faculty of Pharmacy, University of Toronto,
Toronto, Ontario, Canada M5S 2S2, Department of Chemical Engineering
and Applied Chemistry, University of Toronto, Ontario, Canada M5S
1A1, Department of Pharmacology, Faculty of Medicine, University of
Toronto, Canada M5S 1A1
APStracts 2:0234G, 1995.
Intravital epifluorescent microscopy was used to quantitate
microvascular parameters in the single pass, dually perfused rat
liver preparation. Livers perfused via the hepatic artery and portal
vein at physiological pressures and perfusion rates responded to
vasoactive agents and exhibited the hepatic arterial buffer response.
The distribution of arterial blood was found to be highly
heterogeneous, whereas portal venous flow was distributed uniformly.
The intrasinusoidal velocity of FITC-labeled erythrocytes arriving
from the hepatic artery was higher than that arriving from the portal
vein, indicating a shorter transit time for the arterially delivered
FITC-RBCs. Experiments on livers perfused simultaneously via the
hepatic artery and retrogradely via the hepatic vein revealed the
presence of arterio-venous shunts, with some of the arterially
delivered FITC-RBCs reaching the terminal hepatic venules via direct
channels without traversing the sinusoidal bed. In livers perfused
portally only, changes in portal venous flow rate (from 8 to 20
ml/min) produced small changes in perfusion pressure but large
changes in vascular diameters while portal pressure and transit time
of portal blood remained relatively constant. In experiments designed
to identify the location of hepatic vascular resistance, it was
observed that hepatic venular diameters measured in the preparation
under identical pressure and flow conditions were greater during
retrograde than during prograde perfusion, suggesting that the site
of hepatic vascular resistance is presinusoidal or sinusoidal.
Received 7 September 1994; accepted in final form 2 October 1995.
APS Manuscript Number G339-4.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95