Abstract

ABSTRACT. Viable cells were isolated from a 32Pinduced rat osteogenic sarcoma by digestion with collagenase/hyaluronidase followed by centrifugation over Ficoll/Triosil. The cell preparation, which remained viable in terms of glucose consumption for at least 5 h, consisted primarily of tumor cells, the only contamination being approximately 5–10% macrophages. In the presence of 10 mM theophylline cyclic AMP levels were increased by parathyroid hormone (PTH), prostaglandins E1, E2 and F2α, isoproterenol, thyroxine and calcitonin. A range of other hormones did not significantly increase cyclic AMP levels. Only insulin caused a significant increase in cyclic GMP levels in these cells. The effect of PTH was maximal within 5 min of adding the hormone. The lowest effective concentration of PTH was 8 mU/ml and half-maximal stimulation occurred at 100 mU/ml. Responses to calcitonin were small, but agreed with the effects of the hormone on cyclic AMP levels in other systems. The relative potencies of the prostagla...

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