Angiotensin converting enzyme (ACE) is distributed unevenly throuRhout thc human brain. with higher conccntration in the corpus striaturn [4]. Arregui c t al [ I ] have recently described selective depletion of ACE in the corpus striatum in Huntington's chorea. To examine further the angicrtensin system in extrapyramidal disorders, we have studied whether any alterations of brain ACE occur in Parkinson's disease, in which the most pronounced ncuropatholcrgical changes arc located in the substantia nigra-striatum system 1.21.
Postmortem brain samples were obtained from 2 women and 4 men with Parkinson's disease. The mean age was 73 ? 4 years, and the mean duration of the disease was 8 ? 1 years. T w o of the patients had k e n treated with levodopa and benserazide but 4 patients only with anticholinergic drugs. T h e mean interval benvt.cn death and autopsy was 26 2 12 hours. Various regions o f the brain (Table ) were dissected for biochemical analysis. Samples of cerebral cortcx were taken from rhe left frontal lobc.
Correspomiing control brain samples from 6 patients aged 75 -C 6 years without extrapyramidal disordcrs were wkco ar the same time as the parkinsonian postmortem brains became available. T h e mc.m interval between death and autopsy was 36 % 6 hours.
T h e tissucs were homogcnited in 0.1 M Tris-