Brain energy disorders and oxidative stress due to chronic hypoperfusion are considered to be major risk factors in the pathogenesis of dementia. The aim of our study was to evaluate changes of the brain creatine kinase (BB-CK) reaction and mitochondrial respiratory chain function in male Wistar rats exposed to chronic cerebral hypoperfusion. Three-vessel occlusion (3-VO) was accomplished without thoracotomy using a minimally-invasive surgical approach for the occlusion of the brachiocephalic trunk and the left common carotid artery (CCA). The forward rate constant of creatine kinase (k(for)) was measured in vivo by saturation transfer of (31)P magnetic resonance spectroscopy (MRS) at 2 and 10 weeks of permanent 3-VO. The function of the mitochondrial respiratory chain in vitro was assessed polarographically at 10 weeks after 3-VO. When compared to the controls, the significant 42% reduction of k(for) at 2 resp. 10 weeks indicated disorders in brain energy metabolism, which is in agreement with the 12% decrease of the oxidative phosphorylation coefficient (ADP:O) and with the 14% decrease of the oxidative phosphorylation rate (OPR) measured in isolated mitochondria. Oxidative modification of the creatine kinase system (inactivation of enzymes) and metabolic disorders due to chronic 3-VO, thus, may participate in vascular cognitive impairment and neuronal degeneration.