The effects of agents modulating the cytoskeleton, taxol (microtubuli stabilizing), vinblastine (microtubuli destabilizing) and cytochalasin D (actin destabilizing) (10(-6) M each) on enzyme and ATP release as well as on irreversible cell injury were investigated in isolated perfused hypoxic and reoxygenated rat hearts. Enzyme (creatine kinase (CK)) and ATP concentration were assayed in the interstitial transudate and venous effluent. Irreversible cell injury was determined from trypan blue uptake and nuclear staining (NS) of cardiomyocytes in histologic sections. ATP release from nonneuronal cells was only detectable in the interstitial transudate and was not significantly altered by the agents. In controls total CK release (about 4% of total CK) exceeded the percentage of irreversibly injured cells by a factor of 8. Taxol and cytochalasin D abolished the hypoxia/reoxygenation induced interstitial CK release and reduced total CK release to a highly significant extent. The percentage of irreversible injured cells was even more diminished by these agents resulting in a ratio of CK/NS of 40. The effect of cytochalasin D apparently is the consequence of decreased contractile performance as shown by analogous depression by butonedione monoxine (BDM), whereas contractile activity was not altered by taxol. Vinblastine had no influence on CK release but increased the number of irreversibly injured cells significantly. In conclusion, cytoskeletal elements apparently participate in the hypoxia/reoxygenation induced process of release of cytosolic enzymes (CK) and irreversible injury in a different way and extent. Taxol exhibits a cytoprotective effect in isolated perfused rat hearts as evaluated by the extent of enzyme release and irreversible cell injury.