The fermentation diagnosis and histologic studies in blood and the liver of surviving rats after 1 and 2 administrations of a median toxic dose of parathion methyl. 1. Results of studies on the activities of the plasma enzymes AlAT, AsAT, AP, and gamma-GT

Clearly pronounced changes in plasma enzyme activities were observed 24 hours after one and two applications of parathion methyl (PM). The most strongly pronounced rise was in activity of aspartate-amino transferase and was recorded from both sexes. PM application caused sizeable changes in male rats. Comparison between reactions after one and two applications revealed more intensive changes in males after the 1st application. Somewhat larger differences were recordable in some cases between the 1st and 2nd applications. Closer agreement between reaction intensities after the 1st and 2nd PM applications was recordable from female rats. In either sex in response to one single and repeated application parameters returned to normal within nearly one and the same period of time. No secured relationships between activities prior to and after application of PM could be derived from the assays of gamma-glutamyl transpeptidase (gamma-GT). Both increase and decrease of determined enzyme activities were actually recorded. Activities were highly variable in the control groups. Extreme rises were recordable in some cases from both control and experimental groups. No conclusions so far can be drawn as to "normal values" in rat plasma, possible sex-related differences, and behaviour of enzyme activity in response to one single or repetitive applications. Hence, within common investigations of acute toxicity of alkylphosphates, gamma-GT was found to be not suitable for detection of damage to the liver or other organs.