The effects of ischemia on long bone vascular resistance.
An in vitro canine tibia model was used to assess the effects of 48 h of hypothermic (4 degrees C) ischemia on bone vascular resistance and on responsiveness of intraosseous blood vessels to circulating norepinephrine. Three groups of bones were studied: Group I (n = 11), 48 h hypothermic ischemia; Group II (n = 11), 48 h hypothermic ischemia with pretreatment with allopurinol and oxypurinol; and Group III (n = 10), no ischemia. Resting vascular resistance in both ischemic groups (79 and 74 mmHg/ml/min) was significantly higher (p less than 0.0001) than in the nonischemic group (22 mmHg/ml/min). Effects of norepinephrine on vascular resistance were significantly greater in both ischemic groups (p less than 0.004). In all three groups, acetylcholine infusion attenuated the increases in perfusion pressure caused by norepinephrine. This demonstrates secretion of endothelial-mediated relaxing factors (EDRF) and prostaglandin for up to 48 h of hypothermic ischemia. As no significant differences were detected between the two ischemic groups, this study failed to demonstrate any protective effect of xanthine oxidase inhibitors.
Department of Orthopedics, Mayo Clinic, Rochester, MN 55905.
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Wood
D000109:Acetylcholine / Q000494:pharmacology; D000493:Allopurinol / Q000627:therapeutic use; D000818:Animals; D003080:Cold Temperature / Q000009:adverse effects; D004195:Disease Models, Animal; D004285:Dogs; D004342:Drug Hypersensitivity; D007511:Ischemia / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D009569:Nitric Oxide / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology; D010117:Oxypurinol / Q000627:therapeutic use; D012039:Regional Blood Flow / Q000187:drug effects; D015427:Reperfusion Injury / Q000503:physiopathology / Q000517:prevention & control; D013977:Tibia / Q000098:blood supply* / Q000378:metabolism / Q000502:physiology; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014969:Xanthine Oxidase / Q000502:physiology
D009569:Nitric Oxide; D000493:Allopurinol; D014969:Xanthine Oxidase; D010117:Oxypurinol; D000109:Acetylcholine; D009638:Norepinephrine