Quantitative autoradiographic determination of angiotensin-converting enzyme (kininase II) binding in individual rat brain nuclei with 125I-351A, a specific enzyme inhibitor.

We report the localization and characterization of angiotensin-converting enzyme (kininase II) in discrete nuclei from individual rat brains by a quantitative autoradiographic technique coupled to computerized microdensitometry. The enzyme was quantitated by incubation of 16-micron-thick brain sections with 0.07-2 nM of the converting enzyme inhibitor 125I-351A and comparison to 125I-standards. This technique can be applied to the study of other enzymes in single rat brain nuclei.