The effect of dimethylsulfoxide on the calcium paradox.

Reperfusion of isolated rat hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). Experiments were undertaken to study the effect of dimethylsulfoxide (DMSO) on the occurrence of the calcium paradox in rat heart muscle. DMSO (1.4 mol/l) was added to the calcium-free or the reperfusion medium. Cell damage was quantitated in terms of creatine kinase (CK) release, cardiac electrogram (CEG) changes, and ultrastructural damage. Reperfusion with calcium-containing solution without DMSO after calcium-free perfusion with DMSO resulted in massive release of CK, electrical arrest of the ventricles, and formation of contraction bands. Nearly 100% of the cells displayed the calcium paradox damage. Reperfusion with calcium-containing solution with DMSO after calcium-free perfusion without DMSO resulted in a moderate release of CK, and electrical arrest of the ventricles. The myofibrils remained in a relaxed state. Only 4% of the cells displayed the calcium paradox damage. These results indicate that DMSO does not protect rat hearts against the effects of calcium-free perfusion that predispose the myocardium to the calcium paradox. The calcium paradox damage is reduced, however, when DMSO is present during the reperfusion phase.