[Increase in capillary permeability induced by endotoxin: protection with antioxidants and glutathione]

Endotoxin administration increases capillary permeability in experimental animals and this is one of the most relevant events in the pathophysiology of endotoxin shock; the aim of the present experiment was to demonstrate that the action of endotoxin on capillary permeability is due to oxygen-free radicals generation. Experiments were performed on the mesocecum of male Wistar rats; fluorescent labeled bovine albumin (FITC-BSA) was injected intra-arterially to evaluate the capillary permeability; the mesocecum microcirculation was observed by fluorescent light. Permeability was quantified by changes in the number of leaky sites at 10 minute intervals for an hour. The effects of Endotoxin (DIFCO 0111:B4, 30 mg/kg i.a.) were assessed in rats receiving 1) saline, 2) reduced glutathione (250 or 500 mg/kg i.p.), 3) three different nitrones (PBN, DMPO, POBN) (6.25 mg/kg i.p.) whose action is to "trap" oxygen radicals. Capillary permeability largely increased in a few minutes in control rats but it was quite unaffected in rats receiving glutathione or nitrones. As a conclusion the increased capillary permeability observed after endotoxin injection in rats may be due to an oxygen-radicals generation.