K. Metcalf et al., INTRAVENOUS ENDOTOXIN DOES NOT INCREASE TISSUE EXTRAVASATION OF ALBUMIN IN RATS, Acta anaesthesiologica Scandinavica, 42(8), 1998, pp. 966-973
Background: It is unclear whether activation of the inducible nitric o
xide synthase (iNOS) increases or decreases the extravasation of plasm
a. Methods: Chloralose anaesthetised male Wistar rats received E. coli
lipopolysacharide (LPS), 3 mg kg-l i.v., or the corresponding volume
of saline, 3 or 5 h before the end of the experiment. Mean arterial pr
essure (MAP) and heart rate (HR) were recorded. Tissue clearance of ra
dio-labelled albumin, during the last 2 h of each experiment, was dete
rmined by a double-isotope method. In separate animals, the serum conc
entration of nitrite and nitrate was determined, 5 h after LPS or the
solvent. Main Results: LPS initially decreased MAP and lastingly incre
ased HR. In the 3-h LPS animals (n=8), tissue plasma clearance was low
er in the heart and calf muscle and increased only in diaphragm, compa
red to corresponding control animals (n=8). Ln the 5-h LPS rats, clear
ance was lowered (n=8) in the entire gastrointestinal tract and in tes
tes, compared to controls (n=8). The serum nitrite/nitrate concentrati
on was higher in animals given LPS (n=6) than in controls (n=6). Concl
usion: After LPS, tissue clearance of albumin was not increased in any
major tissue, in spite of increased serum levels of NO end products.
Apparently, after activation of iNOS, the augmented release of NO is n
ot necessarily associated with increased albumin extravasation.