Protease inhibition attenuates microvascular dysfunction in postischemic skeletal muscle.
Neutrophils accumulate in skeletal muscle subjected to ischemia-reperfusion and appear to contribute to reperfusion-induced microvascular dysfunction. The overall objective of this study was to assess the role of the neutrophilic hydrolytic enzyme elastase in ischemia-reperfusion-induced granulocyte accumulation and microvascular dysfunction in skeletal muscle. We examined the effect of three structurally unrelated elastase inhibitors [eglin C, MeOsuc-Ala-Ala-Val-CH2Cl (MAAPV), or L-658758], administered at the onset of reperfusion, on neutrophil content and the increase in microvascular permeability induced by 4 h of ischemia and 0.5 h of reperfusion in the isolated canine gracilis muscle. Changes in vascular permeability (1 - sigma) were assessed by determining the solvent drag reflection coefficient for total plasma proteins (sigma) in the following groups: 1) 4.5 h of continuous perfusion (nonischemic), 2) ischemia-reperfusion alone, 3) ischemia-reperfusion + eglin C, 4) ischemia-reperfusion + MAAPV, and 5) ischemia-reperfusion + L-658758. Muscle neutrophil content was monitored by assessing tissue myeloperoxidase (MPO) activity in biopsies obtained at the end of the experiments. In nonischemic muscles, 1 - sigma and MPO activity averaged 0.13 +/- 0.03 and 0.7 +/- 0.2 units/g wet wt, respectively. Ischemia-reperfusion was associated with marked increases in microvascular permeability (1 - sigma = 0.39 +/- 0.02) and muscle MPO activity (8.9 +/- 1.2 units/g wet wt) that were attenuated by eglin C, MAAPV, and L-658758 (1 - sigma = 0.21 +/- 0.01, 0.22 +/- 0.02, and 0.21 +/- 0.03, respectively; MPO activity = 2.7 +/- 0.4, 2.1 +/- 0.8, and 2.8 +/- 1.8 units/g wet wt, respectively). These results suggest that granulocyte accumulation in postischemic skeletal muscle is dependent on the release of elastase from activated phagocytic cells. Moreover, neutrophilic elastase appears to play a major role in reperfusion-induced increases in microvascular permeability in skeletal muscle.
Carden
D L
DL
Department of Physiology and Biophysics, Louisiana State University Medical Center, School of Medicine, Shreveport 71130, USA.
Korthuis
R J
RJ
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D002199:Capillary Permeability; D002511:Cephalosporins / Q000494:pharmacology; D004285:Dogs; D005260:Female; D007511:Ischemia / Q000503:physiopathology*; D019272:Leukocyte Elastase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D018482:Muscle, Skeletal / Q000098:blood supply*; D009504:Neutrophils / Q000201:enzymology; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology*; D011506:Proteins; D015424:Reperfusion; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D015843:Serpins / Q000494:pharmacology
D000590:Amino Acid Chloromethyl Ketones; D002511:Cephalosporins; C102494:O-methylsuccinyl-alanyl-alanyl-valyl-chloromethyl ketone; D011480:Protease Inhibitors; D011506:Proteins; D015842:Serine Proteinase Inhibitors; D015843:Serpins; C028656:eglin proteinase inhibitors; C065332:L 658758; D009195:Peroxidase; D010196:Pancreatic Elastase; D019272:Leukocyte Elastase