Quantitative studies on acid phosphatase in developing rat bones and teeth during hypervitaminosis D

Abstract

The following differences were found between bone and tooth buds with regard to the acid p-nitrophenyl phosphatase activity in whole homogenates and extracts: (a) most of the enzyme in a KCl (0.15 M) homogenate of bone was in a 6000 g min sediment but was extracted with urea, while most of the activity in tooth buds was extracted with KCl and was not affected by urea; (b) the activity in bone was stimulated by both sodium tartrate and sodium chloride in vitro, while the activity in tooth bud was markedly inhibited by sodium tartrate and unaffected by sodium chloride; (c) the activity in bone, but not in tooth buds, was completely inhibited by fluoride in vitro and relatively resistant to heat; and (d) the enzyme activity in bone, but not in teeth, was increased markedly during hypervitaminosis D. The tissue-specific effects of inhibitors in vitro and of vitamin D in vivo are in agreement with previous histochemical studies with α-naphthyl phosphate as substrate. It is concluded that most of the p-nitrophenyl phosphatase activity in bone is due to a tartrate-resistant and heat-resistant enzyme which is different from the tartrate-sensitive and heat-labile enzyme responsible for most of the activity in the odontogenic cells.