Cardiovascular Collapse/Methamphetamine Fatality Figure 1. Methamphetamine dose-dependently and time-dependently elicited mortality and cardiovascular collapse. Temporal changes in survival rate (A), mean arterial pressure (MAP; B), heart rate (HR; C) or power density of the low-frequency (LF) component of systolic blood pressure signals (D) in rats that received (at arrow) intravenous (i.v.) METH or saline (vehicle control). Values are mean 6 SEM, n = 5–62 animals per experimental group. *P,0.05 versus saline group in the Fisher Exact Test (A), or at corresponding time-points in the post hoc Scheff e´ multiple-range test (C–D). B, baseline. doi:10.1371/journal.pone.0030589.g001 Increase of mitochondrial superoxide anion in RVLM In rats that died of METH (24 mg/kg, i.v.), there was also an increase of mitochondria-derived superoxide anion level in RVLM as demonstrated by enzyme-linked immunosorbent assay (ELISA) (Figure 8A) or represented by the intensity of fluorescence from a mitochondrial superoxide indicator (Tyagi et al., 2010), MitoSOX (Figure 8B). Microinjection bilaterally of CoQ10 (7 nmol) or Mito- TEMPO (500 pmol) again significantly blunted those responses (Figures 8A,B). On the other hand, negligible superoxide anion was observed in RVLM (Figures 8A,B) of sham-controls or saline- treated rats. Mitochondrial dysfunction, bioenergetic failure, oxidative stress and necrotic cell death in RVLM underlie METH- induced cardiovascular collapse and mortality Microinjection of CoQ10, Mito-TEMPO or IM-54 bilaterally into RVLM, at a dose that antagonized mitochondrial dysfunc- tion, bioenergetic failure, oxidative stress or necrotic cell death in RVLM (Figure 9), significantly sustained survival (vehicle+METH, 40%; CoQ10+METH, 78%; Mito-TEMPO+METH, 70%; IM- 54+METH, 85%) by antagonizing arterial pressure collapse, asystole and disappearance of power density of the LF spectral component induced by intravenous administration of a lethal dose of METH (24 mg/kg). Discussion A majority of the investigations on METH focuses on the behavioral alterations, physical dependence or psychopathology of withdrawal syndrome and its management that are associated with this psychostimulant. Much less studies are devoted to the mechanisms of METH intoxication despite that it is a common cause of death within the abuse population [4,5]. Based on a fatal METH intoxication model, the present study provided the first demonstration that acute cessation of brain stem cardiovascular PLoS ONE | www.plosone.org 3 January 2012 | Volume 7 | Issue 1 | e30589