An in situ assay system to measure ornithine decarboxylase activity in primary cultures of chicken osteoblasts: effects of bone-seeking hormones.

We present a rapid and uncomplicated in situ assay for measuring ornithine decarboxylase activity in small cell quantities. This method is more economic than the in 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.