Role of c-fibers in the inflammatory response to intratracheal
lipopolysaccharide (lps).
Long, Nancy C., Charles W. Frevert, and Stephanie A. Shore.
Physiology Program Harvard School of Public Health and Boston
University College of General Studies
APStracts 3:0085L, 1996.
We proposed that C-fibers play a role in mediating the inflammatory
response to the intratracheal (IT) instillation of
lipopolysaccharaide, (LPS), a purified form of endotoxin. To test
this hypothesis, we compared the inflammatory response to IT LPS (0.1
to 2.5 mg/kg) in rats whose C-fibers had been destroyed by neonatal
capsaicin treatment to that seen in animals that were treated with
vehicle. Three hours after the instillation of LPS, we assessed
pulmonary inflammation by performing bronchoalveolar lavage (BAL) on
the animals, and measuring the number of neutrophils, the
concentration of protein, as an index of vascular permeability, and
concentration of tumor necrosis factor (TNF). Our results indicate
that capsaicin treatment resulted in more neutrophils, and higher
levels of protein and TNF in the BAL fluid in response to IT LPS,
compared to vehicle-treated rats. We also assessed the production of
inflammatory mediators by alveolar macrophages (AM[phi]) from both
groups of rats incubated with LPS (0.3 to 30 ng/ml) in vitro. We
found a modest increase in the concentration of TNF and nitrite in
the supernatant of macrophages collected from capsaicin-treated rats,
in comparison to vehicle-treated animals. These results are
consistent with the hypothesis that intrinsic differences in the
sensitivity of alveolar macrophages of capsaicin and vehicle-treated
animals contribute to the greater inflammatory response of capsaicin
-treated rat to IT LPS.
Received 16 June 1995; accepted in final form 5 May 1996.
APS Manuscript Number L189-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 17 June 96