The differentiation inducer,dimethyl sulfoxide,transiently increases the intracellular calcium ion concentration in various cell types

Dimethyl sulfoxide (DMSO) initiates a coordinated differentiation program in various cell types but the mechanism(s) by which DMSO does this is not understood. In this study, the effect of DMSO on intracellular calcium ion concentration (Ca²⁺]_i) was determined in primary cultures of chicken ovarian granulosa cells from the two largest preovulatory follicles of laying hens, and in three cell lines: undifferentiated P19 embryonal carcinoma cells, 3T3-L1 fibroblasts, and Friend murine erythroleukemia (MEL) cells. Ca²⁺]_i was measured in cells loaded with the Ca²⁺ -specific fluoroprobe Fura-2. There was an immediate (i.e., within 5 sec), transient, two to sixfold increase in Ca²⁺]_i after exposing all cell types to 1% DMSO. DMSO was effective between 0.2 and 1%. The prompt DMSO-induced Ca²⁺]_i spike in all of the cell types was not prevented by incubating the cells in Ca²⁺ -free medium containing 2 mM EGTA or by pretreating them with the Ca²⁺-channel blockers methoxyverapamil (D600; 100 μM), nifedipine (20 μM), or cobalt (5 mM). However, when granulosa cells, 3T3-L1 cells, or MEL cells were pretreated with lanthanum (La³⁺; 1 mM), which blocks both Ca²⁺ channels and membrane Ca²⁺ pumps, there was a sustained increase in Ca²⁺]_i in response to 1% DMSO. By contrast, pretreating P19 cells with La³⁺ (1 mM) did not prolong the DMSO-triggered Ca²⁺]_i transient. In all cases, the DMSO-induced Ca²⁺]_i surge was unaffected by pretreating the cells with the inhibitors of inositol phospholipid hydrolysis, neomycin (1.5 mM) or U-73, 122 (2.5 μM). These results suggest that DMSO almost instantaneously triggers the release of Ca²⁺ from intracellular stores through a common mechanism in cells in primary cultures and in cells of a variety of established lines, but, this release is not mediated through phosphoinositide breakdown. This large, DMSO-induced Ca²⁺ spike may play a role in the induction of cell differentiation by DMSO. © 1993 Wiley-Liss, Inc.