Journal of Applied Physiology, Vol 71, Issue 5 1830-1835, Copyright © 1991 by American Physiological Society
Fructose 1,6-diphosphate augments paraquat injury in isolated dog lungs
T. Shibamoto and J. C. Parker
Department of Physiology, Shinshu University School of Medicine, Matsumoto, Japan.
Paraquat (PQ; 1,1'-dimethyl-4,4'-bipyridylium dichloride), a widely used
herbicide, causes pulmonary edema by a cyclic oxidation and reduction
reaction with oxygen molecules with the production of oxygen free radicals.
Because fructose 1,6-diphosphate (FDP) has recently been shown to inhibit
the generation of oxygen free radicals by activated neutrophils, we
determined the effects of FDP on PQ-induced increase in microvascular
permeability in isolated blood-perfused dog lungs. Vascular permeability
was assessed using the capillary filtration coefficient (Kf,c) and
isogravimetric capillary pressure (Pc,i). There was no change in these
variables over 5 h in the control lungs treated with saline (n = 5). A
significant increase in Kf,c and a decrease in Pc,i, both of which
indicated increased vascular permeability, were observed at 5 h of
perfusion with 4 x 10(-3) M PQ (n = 5). Unexpectedly, an increase in
microvascular permeability occurred within 4 h after administration of PQ
in the lungs that were pretreated with FDP (2.7-14.2 mM, n = 6). Moreover
the increases of Kf,c in the FDP-pretreated lungs were significantly
greater than those in the lungs treated with PQ alone. Also, the
final-to-initial lung weight ratio of the FDP-pretreated group was greater
than those of the other groups. Thus the FDP dose used in the present study
accentuated rather than prevented the PQ lung injury.
