THE EFFECT OF 1α-HYDROXYVITAMIN D₃ AND CORTISONE ON THE DEVELOPMENT OF CHICK DUODENAL ALKALINE PHOSPHATASE IN ORGAN CULTURE

Abstract

The development of alkaline phosphatase influenced by 1α-OH-D₃ (a synthetic active form of vitamin D₃) and cortisone was studied in chick duodenal organ cultures. The administration of cortisone to the embryo in ovo on the 14th day of incubation resulted in a precocious increase in alkaline phosphatase after 6 days (20-day embryo). When duodena from 14-, 18- and 20-day embryos were cultured in the presence of cortisone, there was no significant enhancement of alkaline phosphatase activity except for a marginal effect observed in the 18-day duodenum. On the other hand, the alkaline phosphatase activity in cultured duodena from 20-day chick embryos was significantly stimulated by the addition of 1α-OH-D₃. The effects of cortisone and 1α-OH-D₃ were not additive. The activity of maltase, another intestinal enzyme, was not influenced by 1α-OH-D₃. Studies on inactivation of alkaline phosphatase by EDTA suggest that the observed increase in alkaline phosphatase activity induced by the administration of 1α-OH-D₃ in vitro may be related to the qualitative changes in the enzyme that take place during development in vivo.