Regional differences in constitutive and induced icam-1 expression
in vivo.
Pan[acute]es, Juli[acute]an, Michael A. Perry, Donald C. Anderson,
Anthony Manning, Barbara Leone, Gediminas Cepinskas, Craig L.
Rosenbloom, Masayuki Miyasaka, Peter R. Kvietys, and D. Neil Granger.
Department of Physiology, LSU Medical Center, Shreveport, LA
71130
APStracts 2:0235H, 1995.
The aim of the present study was to characterize and compare the
expression of ICAM-1 on unstimulated and endotoxin-challenged
endothelial cells in different tissues of the rat. ICAM_1 expression
was measured using 125I labeled anti-rat ICAM-1 mAb, and an isotype
-matched control mAb labeled with 131I (to correct for non-specific
accumulation of the binding mAb). Under baseline conditions, ICAM_1
mAb binding was observed in all organs. The binding of 125I_ICAM_1
mAb varied widely between organs, with the largest accumulation (per
g tissue) in the lung, followed by heart (1/20 lung activity),
splanchnic organs (1/50), thymus (1/100), testes and brain (1/300),
and skeletal muscle (1/800). Endotoxin induced an increase in ICAM_1
mAb binding in all organs except the spleen. Endotoxin-induced
upregulation of ICAM_1 was greatest in heart and skeletal muscle (5
-10 fold), while the remaining organs exhibited a 2-4 fold increase in
ICAM_1 expression. Maximal upregulation of ICAM-1 occurred at 9-12
hours after endotoxin administration. A dose-dependent increase in
ICAM_1 expression was elicited by 0.1-10 _g/kg, with higher doses (up
to 5 mg/kg) producing no further increment. Induction of ICAM-1 mRNA
after endotoxin was observed in all tissues examined (lung, heart,
intestine) and peaked at 3 hours and then rapidly returned to control
levels. These findings indicate that ICAM_1 is constitutively
expressed on vascular endothelium in all organs of the rat and that
there are significant regional differences in the magnitude and time
-course of endotoxin-induced ICAM-1 expression.
Received 20 March 1995; accepted in final form 1 June 1995.
APS Manuscript Number H265-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.