Effects of dimethyl sulphoxide on ATP content and protein synthesis in tetrahymena

The content of ATP in cells exposed for 1 hour to 2.5% and 7.5% dimethyl sulphoxide (DMSO) was 90% and about 80%, respectively, of that in control cells. This difference of about 10% in the ATP content cannot explain the previously reported cessation of food vacuole formation in 7.5% DMSO and the uninhibited function in 2.5% DMSO (NILSSON 1974). However, DMSO had a dose-dependent affect on the rate of turnover of ATP in cell extracts, thus the amount of ATP expended per unit time in 7.5% DMSO is only 60% of that expended by extracts of control cells. The rate of protein synthesis was studied by electron microscope autoradiography which revealed considerably less labelled material in DMSO-treated cells than in control cells. Semi-quantitative estimates showed that cells in 2.5%, 5%, and 7.5% DMSO had a rate of incorporation of the labelled amino acid corresponding to 38%, 31%, and 51%, respectively, of that of control cells; the seemingly high rate of incorporation in 7.5% DMSO may reflect a low internal pool of amino acids in these cells. An additional fine structural detail is the induction of intranuclear fibrous bundles in all concentrations of DMSO. The findings are in accord with a random interference of DMSO, presumably by inducing conformational changes in some macromolecules which affect their cellular function. (author)