Noradrenaline-refractoriness in cultured glioma cells

Rat glioma cells in culture (subclone C6-SK71) respond to 0.1 mM noradrenaline by a 100 fold elevation of the intracellular cyclic AMP concentration, and by a subsequent change in morphology. The glioma cells extend multiple processes to resemble the morphology of normal astrocytes in brain tissue. Evidence is presented that the responses are mediated by way of a beta-adrenergic receptor. Both the biochemical and the morphological responses to noradrenaline are visible within minutes, but the cells revert to the untreated condition within 8 hours. Addition of fresh noradrenaline does not alter the sequence of events. A refractory period in which neither effect could be evoked by a subsequent exposure to noradrenaline was observed to last about 50 hours and was not correlated with a change in the rate of cell growth.