Anin situ assay system to measure ornithine decarboxylase activity in primary cultures of chicken osteoblasts: Effects of bone-seeking hormones

Summary We present a rapid and uncomplicatedin situ assay for measuring ornithine decarboxylase activity in small cell quantities. This method is more economic than thein situ methods described by others. In addition, our system is faster and less complicated since it avoids manipulation of the CO₂-trapping paper. Applying this method we demonstrate that parathyroid hormone, PGE₁, and other inducers of intracellular cAMP levels, like IBMX and forskolin can induce ODC activity in primary cultures of chicken osteoblasts. Salmon calcitonin does not induce ODC activity, and 1,25 (OH)₂D₃ at higher concentrations can even give an inhibition of ODC activity. We confirm the recent findings that ODC activity is also dependent on calcium.