Superoxide dismutase reduces islet microvascular injury induced by streptozotocin in the rat.
Intravenous administration of streptozotocin (STZ) leads to permanent diabetes mellitus in rats. We investigated the possible role of islet microcirculatory changes and free radical formation in this animal model. In vivo fluorescence microscopy was performed for 4 h after administration of STZ. Vascular permeability, capillary blood flow, and endothelial leukocyte adhesion were measured in endocrine and exocrine pancreatic tissue. The earliest microcirculatory event was an increase in vascular permeability in pancreatic islets, with a peak 1 h after STZ administration. The difference between islet and exocrine tissue light intensity was +15.8 +/- 5.6% at t = 60 min. Islet blood flow velocity significantly decreased after 3 h, whereas blood flow in the exocrine pancreas was not affected. Complete stasis of islet blood flow was observed only in rats receiving STZ. Neither increased leukocyte adhesion to islet vascular endothelium nor ischemia-reperfusion phenomena were observed. Prophylactic administration of the radical scavenger superoxide dismutase prevented STZ-induced damage to the islet microcirculation in the initial phase of this model. We conclude that STZ leads to severe microcirculatory disturbances within pancreatic islets in rats. Apparently, these changes are mediated at least in part by free oxygen radicals.
Enghofer
M
M
Department of Medicine I, Johann Wolfgang Goethe University, Frankfurt am Main, Germany.
Usadel
K H
KH
Beck
O
O
Kusterer
K
K
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001808:Blood Vessels / Q000187:drug effects / Q000473:pathology; D002196:Capillaries / Q000502:physiology; D002199:Capillary Permeability / Q000187:drug effects; D002445:Celiac Artery / Q000000981:diagnostic imaging / Q000502:physiology; D002448:Cell Adhesion / Q000187:drug effects; D005260:Female; D007515:Islets of Langerhans / Q000098:blood supply*; D007962:Leukocytes / Q000502:physiology; D008833:Microcirculation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects; D013311:Streptozocin / Q000494:pharmacology*; D013482:Superoxide Dismutase / Q000494:pharmacology*; D014463:Ultrasonography
D001786:Blood Glucose; D013311:Streptozocin; D013482:Superoxide Dismutase