Digoxin effect and imprinting in the unicellular Tetrahymena.

Treatment with digoxin increased, whereas treatment with ouabain decreased, the growth rate of Tetrahymena, but the progeny generations showed an increased mitotic rate after both treatments. A single exposure to digoxin or ouabain accounted for a more than twofold increase in the incorporation (binding) of the cardiac glycosides in the progeny generations.

Effect of diphtheria and tetanus toxoids on the growth of, and imprinting developed in, Tetrahymena.

The growth of Tetrahymena was influenced by both diphtheria and tetanus toxoids; depression occurred at a high and stimulation at a low concentration. Pretreatment with the stimulating concentration of diphtheria toxoid caused a lasting modification of growth rate and development of imprinting that resulted in an enhanced response of the cell at reexposure to the toxoid. Tetanus toxoid failed to induce either switch over of cell function or imprinting.

Influence of benzodiazepine (diazepam) by single and repeated treatment on the growth of Tetrahymena.

Diazepam at 10(-7) M stimulated considerably the growth of Tetrahymena. The growth rate increase was still demonstrable after 3 days (after about 15 generations) and was even greater than initially. A second treatment with diazepam did not furthermore increase the growth rate.

Imprinting, digoxin uptake and storage in Tetrahymena.

Tetrahymenas after a single exposure to high concentration of digoxin, release glycoside into the culture medium even three days after removal of the drug. After nine or fifteen days, however, this effect subsides. Re-administration of digoxin causes the digoxin consumption (storage) of Tetrahymenas to increase. This observation indicates that the digoxin imprinting previously demonstrated in mammals occurs also in Tetrahymena. The experiments raise the possibility that also Tetrahymenas are capable of producing a digoxin-like substance detectable by radioimmunoassay.