Stroke; a journal of cerebral circulation
-
This study investigated whether the nitric oxide synthase inhibitor NG-nitro-L-arginine-methyl ester (L-NAME) would alter blood flow and oxygen balance in the ischemic cerebrocortex of isoflurane-anesthetized Long-Evans rats. ⋯ These observations suggest that despite a decrease in cerebral blood flow, inhibition of nitric oxide synthesis mildly improves the oxygen supply and consumption balance in the ischemic cortex.
-
We previously reported that L-arginine infusion increased pial vessel diameter by nitric oxide-dependent mechanisms, improved regional cerebral blood flow (rCBF) distal to middle cerebral artery (MCA) occlusion, and reduced infarction volume in spontaneously hypertensive rats when administered intraperitoneally before and after MCA occlusion. In this report we extend our findings (1) by examining the time course of L-arginine on rCBF and pial vessel diameter under basal conditions and on rCBF after MCA occlusion and (2) by reproducing the protective effect of L-arginine on infarct volume when given intravenously immediately after the onset of MCA occlusion in both normotensive and hypertensive models of focal cerebral ischemia. ⋯ These studies extend our previous findings by demonstrating that exogenous L-arginine induces sustained rCBF increases in normal brain as well as in a marginally perfused brain region distal to MCA occlusion. Our data in Sprague-Dawley rats support the conclusion that L-arginine-induced increases in rCBF can decrease infarction volume. We conclude that nitric oxide-mediated mechanisms increase rCBF and decrease infarction volume after MCA occlusion in both normotensive and hypertensive animals.
-
We evaluated the utility of blood flow velocity measurements by transcranial Doppler ultrasonography as a tool to indirectly measure cerebral perfusion during cardiopulmonary bypass. ⋯ We can monitor cerebral perfusion and metabolism by measurements of relative velocity and modified cerebral metabolic rate for oxygen during hypothermic cardiopulmonary bypass.
-
We sought to examine the effect of moderate hypothermia (30 degrees C to 32 degrees C) initiated after resuscitation on the scavenging systems of free radicals and lipid peroxidation in canine brain tissue after cardiac arrest and resuscitation. ⋯ Moderate hypothermia initiated after resuscitation can significantly inhibit the accumulation of lipid peroxidation products and the consumption of free radical scavengers in the brain tissue.
-
Cardiopulmonary resuscitation with external chest compression generates low perfusion pressures that may be inadequate for restoring cerebral metabolism and may worsen intracellular pH. We tested the hypothesis that cerebral reperfusion with a low perfusion pressure after arrest restores brain adenosine triphosphate (ATP) and pH to levels attained at the same perfusion pressure without preceding complete ischemia. ⋯ Levels of cerebral perfusion pressure sufficient to maintain cerebral oxidative metabolism without complete ischemia during cardiopulmonary resuscitation are not sufficient to restore metabolism after complete ischemia during cardiopulmonary resuscitation. However, low "trickle" blood flow did not worsen intracellular acidosis.