Abstract
Monoamine Oxidase (MAO) [EC. 1. 4. 3. 4. monoamine: O2 oxidoreductase (deaminating) ] in rat under the several abnormal conditions such as starvation, dehydration or fasting was studied and following results were obtained.
1) During 9 days starvation, rats lost 50% of the body weight. The ratio of organs weight against body weight decreased. Especially in liver, the ratio decreased markedly to about 60% of the control.
2) During 7 days starvation, MAO activity decreased to parallele with the decrease of the organs/body weight ratio and thereafter it increased gradually.
3) Following 9 days starvation, succinic dehydrogenase activity in rat liver increased as same as in case of MAO. On the contrary, remarkable decrease was observed in case of cytochrome oxidase activity.
4) The pattern for MAO, succinic dehydrogenase and cytochrome oxidase activity in liver and brain effected by a 9 days starvation differed notably.
5) The substrate specificity for MAO in rat liver following 9 days starvation was studied. To any substrates tested, MAO activity increased remarkably. When 5-hydroxytryptamine was used as the substrate, MAO activity in brain was approximately 2-fold than that of the control.
6) Michaelis Constants were calculated by the Lineweaver Burk's method. In case of the control, Km value of MAO was 1.0×10-2M, while 7.1×10-3M was calculated in case of 9 th day starvation. Feeding following the starvation caused recovery of Km value to the control level.
