EFFECT OF INTERMITTENT HEPATIC PEDICLE CLAMPING ON FREE-RADICAL GENERATION IN THE RAT-LIVER

Background. Intermittent hepatic pedicle clamping is thought to cause less hepatic reperfusion injury compared with continuous clamping: The mechanisms underlying this difference are unknown. We examined the re lationship between intermittent ischemia/reperfusion and the productio n of free radicals Methods. Alpha-(4-pyridyl 1-oxide)-N-tert-butylnitr one was administered to rats as a spin trap agent. Continuous clamping (15, 30, or 60 minutes) or intermittent clamping (four cycles of 15-mi nute ischemia and 5 or 15 minutes of reperfusion) of hepatic pedicle w as carried out. After reperfusion, free radical production in the live r was measured by an electron spin resonance spectrometer, and the lev el of hepatic injury was evaluated by measuring liver enzyme. Results. Longer periods of ischemia increased free radical production after re perfusion. There was no significant increase in free radical productio n or liver enzymes when the duration of ischemia was 15 minutes. Free radical production and liver damage were significantly less severe in intermittent pedicle clamping than in continuous clamping for 60 minut es, especially when the duration of the reperfusion between four cycle s of ischemia was 15 minutes. Conclusions. These results indicate that intermittent pedicle clamping lessens free radical production when co mpared with continuous clamping; although many free radicals are produ ced.