[Relation between age of mice and activity and characteristics of serum alkaline phosphatase]

Characteristics of serum alkaline phosphatase (SAP) were investigated in five strains of young and old mice (C57BL/6, BALB/c, C3H/Bi, MRL/Ipr, Ipr, NZB). SAP activity was measured and SAP kinetics was automatically measured by a spectrophotometer. The heat stability and the inhibitor, beta-bromotetramisole, sensitivity of SAP were also determined. Activity of SAP in old mice was significantly lower compared to young mice of the same strain (P < 0.01). SAP of young mice was more heat labile and was more sensitive to inhibitor as compared to SAP of old mice.