Dynamic asymmetries in liver tyrosine aminotransferase induction

Changes in liver tyrosine aminotransferase activity were measured in mice and rats following a whole body X-irradiation in order to ascertain the dose-effect relationship. The response was either (1) linear in case of low pulses (25 rad/min); (2) parabolic, indicating the onset of a saturation process in case of medium pulses (60 rad/min), or (3) biphasic, suggesting the cooperation of at least two regulatory mechanisms following longtime exposure to strong stimuli (100 rad/min).