Effect of alpha-methyldopa and alpha-methyl-m-tyrosine on the amount of noradrenaline in the heart and brain of irradiated rats.

Effect of alpha-methyldopa and alpha-methyl-m-tyrosine on the amount of noradrenaline in the heart and brain of rats irradiated with 850 R was investigated. It was established that the application of alpha-methyldopa to the animals irradiated with 650 R caused significant decrease of noradrenaline stores in the heart and brain. Meanwhile, when alpha-methyldopa was applied to the animals irradiated with 850 R, there was no further decreasing of noradrenaline. The different effects may be tentatively explained: in animals irradiated with 650 R the processes of biosynthesis are still going on, while after the dose of 850 R, biosynthesis of catecholamine is badly damaged and the further inhibition of decarboxilase is probably impossible. Alpha-methyl-m-tyrosine caused, also, the strong discharge of noradrenaline storage in the heart and brain of irradiated animals. It is interesting to note there is no significant difference in inhibitory effect on animals irradiated with 650 and 850 R, respectively.