Effect of ifenprodil, a polyamine site NMDA receptor antagonist, on brain edema formation following asphyxial cardiac arrest in rats

Objective: Brain edema occurs in experimental and clinical cardiac arrest (CA) and is predictive of a poor neurological outcome. N-Methyl-D-aspartate (NMDA) receptors contribute to brain edema elicited by focal cerebral ischemia/reperfusion (I/R). Ifenprodil, a NMDA receptor antagonist, attenuates brain edema and injury size in rats after focal cerebral I/R. We assessed the hypothesis that ifenprodil reduces CA-elicited brain edema. Methods: Eighteen male Sprague-Dawley rats were assigned to group 1 (normal control, n = 6), group 2 (placebo-treated CA, n = 6), or group 3 (ifenprodil -treated CA, n = 6). CA was induced by 8 min of asphyxiation and the animals were resuscitated with cardiopulmonary resuscitation (CPR), ventilation, epinephrine (adrenaline), and sodium bicarbonate (NaHCO3)-Ifenprodil of 10 mg/kg or a placebo vehicle was given intraperitoneally 5 min before CA. Brain edema was determined by brain wet-to-dry weight ratio at 1 h after resuscitation. Results: There were no differences between groups 2 and 3 in all physiological variables at baseline. Time from asphyxiation to CA was 201.5 +/- 7.5 s in group 2 and 160.7 +/- 10.4 s in group 3 (P < 0.001). Resuscitation time was 68.2 +/- 13.3 s in group 2 and 92.8 +/- 18.2 s in group 3 (P < 0.05). Ifenprodil decreased mean arterial pressure (MAP) before asphyxiation, from 128 +/- 7 in group 2 to 82 +/- 15 mmHg in group 3 (P < 0.001), and negated immediate post-resuscitation hypertension. Brain wet-to-dry weight ratio was 5.64 +/- 0.44 in group 1, 7.34 +/- 10.95 in group 2 (P < 0.01 versus group 1), and 5.93 +/- 0.40 in group 3 (P < 0.05 versus group 2). Conclusions: Ifenprodil reduces CA-elicited brain edema. In addition, we observed significant hemodynarnic changes caused by ifenprodil. (C) 2004 Elsevier Ireland Ltd. All rights reserved.