EFFECT OF DIMETHYL-SULFOXIDE (DMSO) ON THE ELECTROCARDIOGRAM (ECG) INFREELY MOVING MALE BALB C MICE/

1. Since dimethyl sulfoxide (DMSO) is a solvent which is often used fo r drugs in animal studies, we investigated the effect of a daily admin istration of DMSO on the telemetrically obtained electrocardiogram (EG G) in freely moving male Balb/c mice. 2. During treatment with 4.5 ml 100% DMSO/kg i.p. 5 days per week during 3 weeks, DMSO caused substant ial cardiotoxicity. The ST-interval increase significantly after 1 wee k by 2.2 +/- 1.3 msec and also the ECG wave form changed completely in time. 3. During treatment with 4.5 ml 50% DMSO/kg i.p. 5 days per wee k during 3 weeks, no significant difference was observed compared with the control animals. 4. During the entire study the maximal heart rat e and body weight remained constant in all treated groups. 5. The data indicate that DMSO can not be used in a 100% concentration to dissolv e compounds that are tested for protection against the cardiotoxicity of cytostatics.