Levels of peroxide intermediate radicals, Cu(2+) and superoxide dismutase (SOD) activity were estimated by electron spin resonance (ESR) spectrometry, and levels of copper and zinc were measured by atomic absorption spectrometry in the CSF of rabbits with pentylenetetrazol (PTZ)-induced convulsions. One hundred microliters of CSF was collected until clonic-tonic convulsions occurred following the injection of PTZ solution (3.3%). CSF was collected again 20 min and 60 min after the convulsions. Peroxide intermediate radicals, SOD activity, copper and zinc were found in the rabbit CSF. Peroxide intermediate radicals decreased and SOD activity increased at the onset of convulsions. A large Cu(2+) signal, which was not found in the CSF of normal rabbits, appeared at the same time. These levels recovered to the normal level 20 min after the convulsions, but the copper level decreased. Sixty min after the convulsions, the copper level recovered to the normal level. The ESR spectrum of Cu(2+) at the onset of convulsions was identified as the reduced glutathione-Cu(2+) complex by computer simulation. However, there was no change in the zinc level duirug PTZ-induced convulsions.