The Stability of Angiotensin I Formed at Room Temperature in the Presence of Ethylenediaminetetraacetate to Subsequent Incubation at 37 °C

It has been reported that plasma renin activity values obtained from samples containing ethylenediaminetetraacetate (EDTA) and which have been allowed to remain at room temperature for 24-48 hours prior to incubation and assay are spuriously low. Since plasma renin activity is often measured in specialised centres, considerable time delays in sample transit may be difficult to avoid. We, therefore, investigated these findings using plasma samples kept at room temperature for varying times and subsequently incubated at 37 degrees C. From these studies we conclude that plasma renin activity is not significantly affected by pre-incubation at room temperature for periods up to 48 hours. However, the precision of the assay is likely to be poorer in specimens pre-incubated at room temperature. These results are supported by the finding that there is no loss of angiotensin I upon incubation and assay of samples containing pepstatin A.