The optimum pH of serum alkaline phosphatase after induced cholestasis in the male rat, mouse and rabbit.

The optimum pH of serum alkaline phosphatase (alk. P., EC 3.1.3.1) was investigated in adult male rats, mice and rabbits after fasting or after the induction of cholestasis by a single oral dose of 200 mg/kg alpha-naphthylisothiocyanate (ANIT). The nature of serum alk.P. was also studied with the inhibitory effects of three L-amino acids (L-phenylalanine, L-homoarginine and L-cystine) and by electrophoresis. In the rat, fasting as well as ANIT-treatment shifted the optimum pH of alk.P. from 9.4 to 10.0 due to a decrease in intestinal isoenzymes or due to newly appeared liver isoenzymes, while no shifting occurred in mouse and rabbit.