Abstract
It is well known that a significant activity of inducible enzyme is not detectable in a developing liver, and the activity is markedly increased within a certain duration of newborn life. However, the exact mechanism is poorly understood on such a phenomenon.
The purpose of the present paper is to demonstrate the significance of liver maturity on the increasing enzyme activity in a developing liver and a regenerating one. The following experiment was carried out to measure tryptophan pyrrolase activity and thymidine kinase activity as a parameter of DNA synthesis in each period of these livers.
Characteristic findings were present in correlation between tryptophan pyrrolase activity and thymidine kinase activity in these livers. That is, in the regenerating liver, decrease of tryptophan pyrrolase activity and its response to glucocorticoid were in proportion to elevated activity of thymidine kinase. And in a newborn liver also, a similar correlation was found out.
Therefore, the detectable value of tryptophan pyrrolase activity appears when the thymidine kinase activity arrives at the adult level of thymidine kinase activity.
The low activity of tryptophn pyrrolase and poor response to glucocorticoid in the developingliver were thought to be due to immaturity of the liver cells in rapid growth.
