2007 North American Congress of Clinical Toxicology Annual Meeting, Louisiana, United States Of America, 19 - 24 October 2007, vol.45, no.1, pp.629
Background: The aim of the study was to evaluate the effects of different doses of an adenosine
A1 selective agonist phenylisopropyl adenosine (PIA), on metamidophos-induced cholinergic
symptoms, mortality, diaphragm muscle necrosis, brain antioxidant enzyme activities and
thiobarbituric acid reactive substances (TBARS) levels. Methods: Metamidophos 20 mg/kg
p.o. followed by 1 ml/kg 0.9 % sodium chloride, 1 mg/kg, 2 mg/kg, 3 mg/kg or 5 mg/kg PIA,
i.p. were given to the rats (n = 8 in each group), respectively. Initial times for clinical signs and
diaphragma necrosis were compared with Kruskal-Wallis Analysis. Clinical signs between
groups were compared with Fisher’s Exact Test. Survival analysis was based on the Kaplan
Meier procedure. Mann-Whitney U test was used to compare brain antioxidant enzyme activities and TBARS levels in groups. Results: Initial time of clinical signs including chewing,
salivation and convulsion were delayed in the groups that treated with 1 or 5 mg/kg PIA, 1 or 2
mg/kg PIA and 1 mg/kg PIA (p 0.05, p < 0.01, p < 0.01, p < 0.01, p < 0.05), respectively. PIA
was effective to reverse the necrotic changes in diaphgram muscle induced by metamidophos
significantly in all treatment groups (p < 0.01). Brain TBARS levels were significantly
increased after the metamidophos poisoning (p < 0.001). PIA (2 to 5 mg/kg) significantly
decreased in brain TBARS levels compared to 0.9 % sodium chloride treated rats (p < 0.001).
Discussion: Although different doses of PIA reduced the OP- induced oxidative stress and diaphragm necrosis, a single dose of PIA was not able to recover cholinergic symptoms of metamidophos poisoning. Conclusion: Cumulative or repeated dose regimen of PIA might be more
effective to prevent symptoms of metamidophos poisoning in rats.