M. Suematsu et al., SPATIAL AND TEMPORAL CORRELATION BETWEEN LEUKOCYTE BEHAVIOR AND CELL INJURY IN POSTISCHEMIC RAT SKELETAL-MUSCLE MICROCIRCULATION, Laboratory investigation, 70(5), 1994, pp. 684-695
BACKGROUND: Although leukocyte adhesion and capillary plugging are pos
tulated to play a role in postischemic tissue injury, there is only li
mited evidence demonstrating the relationship between tissue leukocyte
accumulation and cell injury in terms of their temporal sequence and
spatial distribution. EXPERIMENTAL DESIGN: This study was designed to
study in vivo neutrophil behavior and its correlation with cell injury
in postischemic skeletal muscle microcirculation. The microcirculatio
n of the rat spinotrapezius muscle was observed in vivo using dual-col
or digital microfluorography to simultaneously visualize leukocyte tra
ffic and cell death (irreversible nuclear damage) on the basis of carb
oxyfluorescein diacetate succinimidyl ester and propidium iodide, resp
ectively. A 1-hour period of hemorrhagic hypotension (40 mm Hg) follow
ed by reperfusion was carried out to induce muscle injury. RESULTS: Hy
potension was followed by an increase in leukocyte recruitment in two
different ways: capillary obstruction and venular adhesion. Upon reper
fusion, a majority of the leukocytes were initially dispersed from the
muscle capillaries and venules, but then the number of leukocytes plu
gging capillaries and adherent to venules increased again in a time-de
pendent manner. The number of leukocytes obstructing capillaries was c
losely correlated with the postischemic systemic blood pressure. The c
ell injury became detectable initially at the end of the hypotensive p
eriod and then increased explosively after reperfusion before a signif
icant leukocyte accumulation. Reperfusion-induced early nuclear injury
was seen predominantly in reperfused capillaries without plugging leu
kocytes. A majority of the initially damaged nuclei were those of myoc
ytes in the pericapillary space, but no nuclei of capillary endotheliu
m was involved. Sodium (-)-8-(3-methoxy-4-phenylsulfinylphenyl) pyrazo
lo [1,5-a]-1,3,5-triazine-4-olate monohydrate, a novel inhibitor of xa
nthine oxidase, significantly attenuated the early increase in muscle
injury and subsequent venular leukocyte adhesion after reperfusion. CO
NCLUSIONS: These results suggest the involvement of an endothelium-dep
endent mechanism involving xanthine oxidase in postischemic irreversib
le myocyte injury. It is conceivable that leukocytes adherent to venul
es as well as those plugging capillaries play only minor roles in the
initial mechanism of reperfusion injury.