[Deamination reactions involving several nitrogen compounds and mammalian radioresistance]

Inhibition of monoamine oxidase (substrates tyramine or serotonin) with simultaneous appearance of diamine oxidase (substrates histamine or putrescine) and distinct increase in AMP-deaminating activities were found after total body X-ray irradiation (700 r) of white mice or rats in mitochondrial fractions isolated from their liver and intestines. These impairments in deamination of nitrogenous compounds in liver mitochondria of guinea pigs, which are must less radioresistant as compared with mice or rats, were noted after the irradiation at a dose 300 r, but in the liver mitochondria of mongolian gerbyls (Mariones unguiculatus), which are highly radioresistant, the irradiation even at a dose 1500 r did not cause appearance either of histamine or of AMP-deaminating activities while the decrease in the monoamine oxidase activity was not statistically significant. Feeding to the mice the grasses, which comprize the fodder of mongolian gerbyls under natural conditions, increased radioresistance of the animals and prevented at the same time appearance in the mitochondrial fractions of liver and intestines of those impairments in deamination of nitrogenous compounds which accompanied development of irradiation injuries.