Effects of dimethylsulfoxide on isolated smooth muscle contractility and antioxidative enzymes activity

M Slavić1, Z Oreščanin-Dušić1, A Nikolić-Kokić1, S Milovanović3, A Mijušković1, R Radojičić2, D Blagojević1, M Spasić1. 1University of Belgrade, Institute for biological research “ Sini š a Stankovi ć” , Physiology, 11060, Serbia, 2University of Belgrade,Faculty of Biology, Physiology, 11060, Serbia, 3University of Eastern Sarajevo, Faculty of Medicine, Fo č a, Pharmacology, Bosnia and Herzegovina

Dimethylsulfoxide (DMSO) is a small molecule with a hydrophilic sulfoxide group and two hydrophobic methyl groups that is widely used as polar aprotic solvent for water-insoluble chemicals. DMSO is employed in medicine due to its analgesic properties and is also considered to have hydroxyl radical scavenging capacity. In the United States, DMSO received approval from the FDA for use in the treatment of interstitial cystitis by intravesicular administration. There are several reports indicating DMSO relaxing effects on different types of smooth muscles.

In this work, we investigated effects of DMSO on contractile activity of isolated uteri and ilei from Wistar rats. According to DMSO antioxidant properties and the fact that redox active molecules could influence signal transduction we also examined the influence of DMSO on antioxidant status of treated tissues.

The effect of DMSO on smooth muscle contractions (spontaneous active and potassium chloride [KCl] induced tonic contractions) were investigated by addition of following cumulative doses (%, v/v): 0.05, 0.05, 0.1, 0.4, 0.8, 1.6, 2, 2, 2 of DMSO for two hours in isolated organ baths. Tonic contractions were induced by addition of a single dose of 100mM KCl and served as a control for KCl induced tonic contractions. Seven to ten samples were used per experiment. After treatments, tissues were homogenized and centrifuged, and the activity of antioxidant enzymes: CuZnSOD (copper-zinc superoxide dismutase), MnSOD (manganese superoxide dismutase), GSH-Px (glutathione peroxidase) and GR (glutathione reductase) in supernatant was determined.

Effects on smooth muscle contractions were analyzed by two-way ANOVA using treatment and dose as factors and were considered statistically significant when p<0.05. The activities of antioxidant enzymes were compared using one-way ANOVA followed by Tukey’s HSD post-hoc test (significance p<0.05).

Our results showed that dimethylsulfoxide dose-dependant relaxed smooth muscles of both uterine and ileum regardless the type of contraction (significant ANOVA dose effect, p<0.001, no significant ANOVA type of contraction effect). This points out its general relaxing properties in contractile tissues. This effect is followed by significant changes in antioxidant enzymes activity when expressed per mg of tissue proteins. In uterine tissue, DMSO induced elevation of GR activity (p<0.01) in spontaneously active muscles and elevation of CuZnSOD, GSH-Px and GR activities in KCl-induced contractions (p<0.001). In both type of ileum contractions, there was an elevation in the activity of the all essayed enzymes [CuZnSOD (p<0.001), MnSOD (p<0.001), GSH-Px (p<0.001) and GR (p<0.01)] in comparison to control. However, when activity was expressed per g of wet tissue, comparison of means showed no changes in the activity of the all measured enzymes, suggesting general DMSO effects on different types of cellular proteins. Our results suggest that 9% dimethylsulfoxide could cause oxidative stress i.e increased production of reactive oxygen species in active smooth muscles, but by different ROS mediated processes. On the other hand, DMSO could influence Ca+2 intracellular sensitivity and ATP metabolism suggesting indirect redox active pathways of DMSO action. However, these effects are tissue- and type of contraction-specific, which should be taken in consideration in a treatment with this substance.