OBJECTIVETo establish and compare three in vitro screening models of angiotensin converting enzyme inhibitors (ACEI), and provide methodological basis for screening ACEI drugs from Chinese herbal medicine.

METHODThree screening models were established using rat serum, pure angiotensin converting enzyme (ACE) and crude extract enzyme from rabbit lung as enzyme sources, respectively, with corresponding testing methods, and captopril as the positive drug.

RESULTThe IC50 of captopril was 2.30 nmol x L(-1) using rat serum as the enzyme; and 1.04 nmol x L(-1) for ACE pure enzyme; and 1.40 nmol x L(-1) for crude extract enzyme from rabbit lung.

CONCLUSIONResults from the three screening models were all in accordance with literature reports. These models can be applied to in vitro pharmaceutical screening. The selection of suitable screening model depend on the experimental situation and the inherent characters of models.