Inhibition of growth of C6 astrocytoma cells by inhibitors of calmodulin

We evaluated the effect of several classes of calmodulin inhibitors on the activity of calmodulin prepared from C 6 astrocytoma cells and studied the activity of these drugs as inhibitors of the growth of C 6 cells in tissue ture. There was a good correlation between the activity of the drugs as inhibitors of calmodulin and their activity as inhibitors of cell growth. The most potent compounds were calmidazolium and melittin as compared to the phenothiazines, trifluoperazine, chlorpromazine, chlorpromazine-sulfoxide or the diphenylbutylpiperidine, pimozide. The mechanism by which the inhibition of calmodulin leads to the death of cells could not be attributed entirely to inhibition of the calmodulin-sensitive cyclic nucleotide phosphodiesterase.