DIASPIRIN CROSS-LINKED HEMOGLOBIN (DCLHB(TM)) - ABSENCE OF INCREASED FREE-RADICAL GENERATION FOLLOWING ADMINISTRATION IN A RABBIT MODEL OF RENAL ISCHEMIA AND REPERFUSION

In control rabbits, a renal ischemia of 60 min followed by 10 min of r eperfusion resulted in an enhanced free radical production in cortical tissue, as assessed by a significant decrease of free glutathione (42 %), protein-bound GSH (17%), and vitamin E (49%). In contrast, catalas e or glutathione peroxidase activities were not affected by these expe rimental conditions. Free radical production in this model was also me asured directly using electron spin resonance (ESR) spectroscopy assoc iated with a PEN (alpha-phenyl N-tert-butyl-nitrone) spin trap agent i n the venous blood arising from the ischemic kidney. The signal consis ted of a triplet of doublets. In contrast, no signal could be detected in control blood samples taken prior to inducing ischemia. The burst of free radical production occurred in the early phase after restorati on of flow in the kidneys rendered ischemic, as evidenced by a signal of weak intensity which generally appeared within the third minute aft er reperfusion and progressively increased to form a well-defined asym metric signal following 10 min of reperfusion. The precise nature of f ree radicals trapped by the PBN agent remains, however, to be elucidat ed, but analysis of the coupling constants (a(N) = 14.5-15 G; a(beta)( H) = 2.5-3 G) and asymmetry of the central doublets suggests that the ESR signal may arise from a nitroxy-radical adduct resulting from the spin trapping by PBN of both oxygen- or carbon-centered radicals of li pidic origin. As evidenced by both direct and indirect measurements, e xchange of rabbit blood immediately after inducing renal ischemia with 30 ml/kg of Diaspirin Crosslinked Hemoglobin (7.5 g/dl in lactated el ectrolyte) or human serum albumin (7.5 g/dl in lactated electrolyte) d id not exacerbate free radical production mediated by an ischemia repe rfusion phenomenon, a typical situation found in a resuscitation setti ng.