Sustained complete autonomic blockade.

1. A 3-hr period of complete autonomic blockade was induced in anaesthetized sheep and dogs using a continuous intravenous infusion of trimetaphan camphorsulphonate and atropine. Circulatory, respiratory and metabolic parameters were studied over 24 hr or until the animal died, whichever came first.2. After termination of the blockade all animals remained hypotensive and within a few hours all died in irreversible shock which was not accompanied by any of the otherwise characteristic respiratory or metabolic consequences of circulatory failure.3. Administration of trimetaphan alone for a similar period was innocuous.4. When during complete autonomic blockade a continuous infusion of dopamine or hypertensin was additionally administered mortality rate was halved but all survivors remained hypotensive.