Adhesion Molecules in Decompression Sickness and Ischemia Reperfusion Injury - Adhesion Molecules - page 173

liver, and skeletal muscle (Dore-Duf y et al. 1999). Lungs (the ultimate i lter of
venous blood) and the liver (the ultimate i lter of portal blood l ow) are especially
targeted by leukocyte aggregation in severe neurological DCS in pigs (Nyquist
et al. 2004). In our study, macrophages were found near vessels, suggesting the
migration of immune cells to the site of inl ammation. A signii cant increase in
ICAM-1 levels by 24 hr at er decompression may also suggest a local response
by individual muscle cells. Sections of quadriceps were stained with hematoxylin
and eosin (H&E). H&E-stained sections of the quadriceps of rats sacrii ced at
24 hr post decompression showed macrophages located near blood vessels, which
was not common in control slides (Fig. 1) ; the blood vessels appeared swollen
in comparison with those seen in muscle tissue from control rats (rats held in
the chamber at 1 ATA but not decompressed). Capillaries in quadriceps tissue
of rats exposed to 4 ATA and rapidly decompressed appeared swollen (diameter
10 μm) at 24 hr following decompression. h is swelling of the vessels was not
observed in the vessels of control rats, which remained approximately 7 μm in
diameter, or in vessels from skeletal muscle tissues from rats exposed to 2 or 3
ATA (Fig. 1) . h e Masson's Trichrome stain used to stain sections of the lungs
contains four dif erent dyes (fast green, hematoxylin, acid fuchsin and xylidine
ponceau) enabling observation of specii c cell types and organization of connective
tissue. h e trichrome stain of the lung tissues of the experimental and control
rats revealed many cell types such as macrophages, neutrophils and eosinophils
(Fig. 2) . h e lung tissues from control rats as well as experimental rats had many
macrophages located in the alveoli. Notably the alveolar walls of rats exposed to 2
(approximately 3 μm), 3 or 4 ATA (approximately 10 μm), rapidly decompressed
and sacrii ced at 6 or 24 hr, were swollen when compared to alveoli from control
rats (< 1 μm).
Key Points
• We (Bigley et al. 2008) identii ed changes in inl ammatory mediators during
the 24 hr period immediately following compression-decompression of
female Sprague-Dawley rats.
• Increased levels of inl ammatory cytokines, TNF-α, IL-6, and IFN-γ were
detected in the circulation 6 hr at er decompression, while increased levels
of only IL-6 were observed at 24 hr.
• Signii cant increases in expression of E-selectin, L-selectin, and ICAM-1
were observed immunohistochemically in the lungs and brains of rapidly
decompressed rats 6 hr at er exposure to 2 , 3, or 4 ATA. h ese levels drop
by 24 hr.
• Greater increases in expression of E-selectin and L-selectin around vessels
and connective tissue were seen at 24 hr at er decompression in the
quadriceps of rats exposed to either 3 or 4 ATA.