TY - JOUR
T1 - Low-flow reperfusion after myocardial ischemia enhances leukocyte accumulation in coronary microcirculation
AU - Ritter, Leslie S.
AU - Mcdonagh, Paul F.
PY - 1997
Y1 - 1997
N2 - During early reperfusion after myocardial ischemia, the mechanisms responsible for leukocyte accumulation in the heart are unclear. We examined the effects of reducing coronary blood flow during reperfusion on leukocyte accumulation in coronary capillaries and postcapillary venules. Isolated rat hearts were perfused for 30 min and then subjected to 30 min of 37°C, no- flow ischemia. The deposition of fluorescently labeled leukocytes was observed directly in coronary capillaries and venules using intravital microscopy after 5, 20, and 35 min of reperfusion. Blood cell velocity was measured in venules after 5 min of reperfusion (R5) and shear rate (s-1) was calculated. Four groups were studied: nonischemic control (NIC) hearts and postischemic hearts reperfused at full flow (I/R100) and at 50 and 10% of full flow (I/R50 and I/R10, respectively). In I/R100 hearts, there was a significant increase in leukocyte trapping in capillaries compared with the NIC group (R5: 5.7 ± 0.6 vs. 2.0 ± 0.4 leukocytes/capillary field, respectively; P < 0.05). However, the increase in leukocyte adhesion to venules was not statistically significant compared with NIC (R5: 3.2 ± 0.4 vs. 1.5 ± 0.6 leukocytes/100-μm venule, respectively; P < 0.2). In I/R50 hearts, a further increase in leukocyte accumulation occurred in the capillaries but not in the venules. However, in I/R50 hearts, there was a statistically significant increase in both capillaries (R5: 9.2 ± 0.8; P < 0.05) and venules (R5: 4.4 ± 0.5; P < 0.05). When leukocyte margination in coronary venucles was examined as a function of venular shear rate, a significant correlation (r = 0.99, P < 0.05) was found. These results suggest that, after ischemia, a reduction in reflow enhances leukocyte trapping in capillaries and that leukocyte adhesion in venules is inversely related to shear rate. Enhanced leukocyte accumulation may in turn increase the leukocyte contribution to early reperfusion in jury in the heart.
AB - During early reperfusion after myocardial ischemia, the mechanisms responsible for leukocyte accumulation in the heart are unclear. We examined the effects of reducing coronary blood flow during reperfusion on leukocyte accumulation in coronary capillaries and postcapillary venules. Isolated rat hearts were perfused for 30 min and then subjected to 30 min of 37°C, no- flow ischemia. The deposition of fluorescently labeled leukocytes was observed directly in coronary capillaries and venules using intravital microscopy after 5, 20, and 35 min of reperfusion. Blood cell velocity was measured in venules after 5 min of reperfusion (R5) and shear rate (s-1) was calculated. Four groups were studied: nonischemic control (NIC) hearts and postischemic hearts reperfused at full flow (I/R100) and at 50 and 10% of full flow (I/R50 and I/R10, respectively). In I/R100 hearts, there was a significant increase in leukocyte trapping in capillaries compared with the NIC group (R5: 5.7 ± 0.6 vs. 2.0 ± 0.4 leukocytes/capillary field, respectively; P < 0.05). However, the increase in leukocyte adhesion to venules was not statistically significant compared with NIC (R5: 3.2 ± 0.4 vs. 1.5 ± 0.6 leukocytes/100-μm venule, respectively; P < 0.2). In I/R50 hearts, a further increase in leukocyte accumulation occurred in the capillaries but not in the venules. However, in I/R50 hearts, there was a statistically significant increase in both capillaries (R5: 9.2 ± 0.8; P < 0.05) and venules (R5: 4.4 ± 0.5; P < 0.05). When leukocyte margination in coronary venucles was examined as a function of venular shear rate, a significant correlation (r = 0.99, P < 0.05) was found. These results suggest that, after ischemia, a reduction in reflow enhances leukocyte trapping in capillaries and that leukocyte adhesion in venules is inversely related to shear rate. Enhanced leukocyte accumulation may in turn increase the leukocyte contribution to early reperfusion in jury in the heart.
KW - Capillaries
KW - Heart
KW - Rat
KW - Venules
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U2 - 10.1152/ajpheart.1997.273.3.h1154
DO - 10.1152/ajpheart.1997.273.3.h1154
M3 - Article
C2 - 9321802
AN - SCOPUS:33751259408
SN - 0363-6135
VL - 273
SP - H1154-H1165
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 3 42-3
ER -