Pre-sinusoidal vessels predominantly contract in response to
norepinephrine, histamine, and kcl in rabbit liver.
Shibamoto, Toshishige, Hong-Gang Wang, Takashige Miyahara, Satoshi
Tanaka, Hisao Haniu, and Shozo Koyama.
Department of Physiology, Division 2, Shinshu University, School of
Medicine, Matsumoto 390-8621, Japan
APStracts 6:0270A, 1999.
In rabbit livers, it is not well known which segments of the hepatic
vasculature are predominantly contracted by various vasoconstrictors.
We determined effects of histamine, norepinephrine and KCl on the
hepatic vascular resistance distribution in isolated rabbit livers
perfused via the portal vein with 5% albumin-Krebs solution at a
constant flow rate. The hepatic capillary pressure was measured by
the double vascular occlusion pressure (Pdo) and was used to
determine the portal (Rpv) and hepatic venous (Rhv) resistances. A
bolus injection of either histamine or norepinephrine dose
-dependently increased the portal vein pressure but not Pdo, resulting
in a dose-dependent increase in Rpv, and no changes in Rhv. KCl (50
mM), when injected in anterogradely perfused livers, contracted the
pre-sinusoidal vessels selectively with liver weight loss. Although
KCl significantly increased Rhv in retrogradely perfused livers, the
increase in Rpv by 400% of baseline predominated over the increase in
Rhv by 85% of baseline. In the retrogradely perfused livers KCl
produced an initial liver weight loss followed by a profound weight
gain. We conclude that histamine and norepinephrine selectively
contract the pre-sinusoidal vessels. The results on KCl effects
suggest that this selective pre-sinusoidal constriction might be
possibly due to predominant distribution of functionally active
vascular smooth muscle in the pre-sinusoidal vessels rather than the
hepatic vein in rabbit livers.
Received 2 November 1998; accepted in final form 11 June 1999.
APS Manuscript Number A996-8.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1999 The American Physiological Society.
Published in APStracts on 25 June 1999