Demonstration of in vivo effects of ACE inhibitors by the use of autoregressive modelling.

We investigated, with use of a technique of feedback analysis, the dynamic changes in and around the renin-angiotensin system in vivo induced by ACE inhibition. Prolonged studies were performed over a half year on rabbits, which were treated by daily injections of saline or one of the inhibitors as follows: captopril, foroxymithine, histargin and pepstatin. In spite of the apparently bizarre movements of the raw data, the analysis with autoregressive modelling unveiled the different modes of feedback regulations of the renin-angiotensin system under the influence of the various inhibitors. In order to interpret the in vivo actions of enzyme inhibitors, it seems essential to take feedback regulations into consideration.