Carnitine treatment for stroke in rats.

Changes in the concentrations of carnitine, long-chain acylcoenzyme A, and long-chain acylcarnitine in ischemic myocardium parallel those in ischemic brain. Since carnitine treatment reverses these changes and improves function in ischemic hearts, we examined whether carnitine given to rats before focal cerebral ischemia (produced by tandem right common carotid artery and middle cerebral artery occlusion) alters infarct volume in four separate experiments. Mannitol was used to control for the osmotic effect of carnitine on brain edema in one experiment. While carnitine was found to significantly decrease infarct volume compared with saline in one experiment (p less than 0.05, Student's t test), this result could not be replicated in the subsequent three experiments. Because the positive treatment effect was not reproducible despite similar experimental conditions, the result of the first experiment was attributed to a type I error. Mannitol also showed no significant effect on infarct volume. This study emphasizes the need for concurrent controls with each group of treated animals and the need for replicating the results of a single experiment when testing for drug efficacy in animal models of focal cerebral ischemia.