Effect of dimethylsulfoxide on the intestinal sugar transport

Inhibiting ice recrystallization and optimization of cell viability after cryopreservation

The ice recrystallization inhibition activity of various mono- and disaccharides has been correlated with their ability to cryopreserve human cell lines at various concentrations. Cell viabilities after cryopreservation were compared with control experiments where cells were cryopreserved with dimethylsulfoxide (DMSO). The most potent inhibitors of ice recrystallization were 220 mM solutions of disaccharides; however, the best cell viability was obtained when a 200 mM d-galactose solution was utilized. This solution was minimally cytotoxic at physiological temperature and effectively preserved cells during freeze-thaw. In fact, this carbohydrate was just as effective as a 5% DMSO solution. Further studies indicated that the cryoprotective benefit of d-galactose was a result of its internalization and its ability to mitigate osmotic stress, prevent intracellular ice formation and/or inhibit ice recrystallization. This study supports the hypothesis that the ability of a cryoprotectant to inhibit ice recrystallization is an important property to enhance cell viability post-freeze-thaw. This cryoprotective benefit is observed in three different human cell lines. Furthermore, we demonstrated that the ability of a potential cryoprotectant to inhibit ice recrystallation may be used as a predictor of its ability to preserve cells at subzero temperatures.

DMSO as a vehicle for central injections: tests with feeding elicited by norepinephrine injected into the paraventricular nucleus

Dimethyl sulfoxide (DMSO) is becoming increasingly popular as a vehicle in studies employing central injections. The aim of the present study was to determine whether the vehicle required for solubilization of substances for central injection [75% DMSO and 25% artificial CSF (aCSF)] would alter the well-characterized stimulatory response to norepinephrine (NE) injected into the paraventricular nucleus (PVN) on short-term food intake. To evaluate its suitability, we compared the effects of repeated unilateral injections of NE dissolved in two different vehicles (100% aCSF or 75% DMSO, 25% aCSF), in separate groups of animals every 48 h over a 30-day period. NE (40 nmol) stimulated food intake by approximately sevenfold compared to either vehicle alone, and the stimulatory effect was similar whether aCSF or 75% DMSO was used as a vehicle. Furthermore, the NE-induced feeding did not vary in magnitude across a series of 13 tests. These results suggest that 75% DMSO is a suitable vehicle for administering NE (and likely other water-insoluble substances)in small volumes of 0.3 microl into specific brain regions.

The effect of dimethyl sulfoxide on the neuronal excitability and cholinergic transmission in Aplysia ganglion cells

The effects of DMSO on single nerve cells of Aplysia were investigated by various electrophysiological methods. 1. Although the increase in permeability of the biological membranes produced by DMSO has been well documented, we found that DMSO at concentration of less than 20% actually decreases the permeability of the neuronal membranes, probably toward potassium and chloride ions. This change in ionic permeability reversibly depolarizes the resting membranes and makes the neurons more excitable. 2. The falling phase of the spike is prolonged by 8% DMSO, because it blocks the active increase in potassium permeability. This change suppresses the high frequency discharge, because the refractory period of each spike is increased. Neither the rising phase nor the absolute firing level is appreciably altered by DMSO when these are examined after the depolarization is cancelled. 3. Dilute DMSO (less than 1%) facilitates cholinergic trasmission because it blocks ACh-esterase activity. DMSO at concentrations of more than 10% ultimately blocks cholinergic transmission entirely, because it also depresses cholinoceptive receptor activity (probably by allosteric interaction). The action of 1-10% DMSO is complicated, because both facilitatory and inhibitory effects take place at the same time. 4. In cholinergic synapses, excitatory transmission is more susceptible to DMSO than inhibitory transmission. This is because the activity of the excitatory receptor is blocked more readily than that of the inhibitory receptor. The depressing effects of DMSO are not specific to the cholinergic system, however, since the activities of GABA and glutamate receptors are similarly depressed.