Blood platelets and angiotensin II.

: To investigate whether human blood platelets contain angiotensin II, platelets were isolated from platelet-rich plasma and resuspended in buffer solution. No angiotensin was detectable by radio-immunoassay in this suspension. However, after sonification all samples appeared to contain significant amounts of angiotensin II. This amount was not reduced by the addition of angiotensinase inhibitors, thus ruling out an assay artefact due to breakdown of tracer. Subsequent experiments showed that the immunoreactive material behaved similarly to standard angiotensin II in several respects.