title: Cryoactivation of renin in plasma from pregnant and nonpregnant subjects, and its control.
abstract: Plasma renin activity increased by a mean of 7% from baseline values when blood from nonpregnant persons was kept at 0 degrees C for 5 h before incubation. Freezing chilled plasma and thawing it before incubation resulted in a mean increase of 11%. The same procedures used on plasma from normal pregnant women produced mean increases in plasma renin activity of 44 and 89%, respectively. If blood from pregnant women was kept at 0 degrees C for 5 h, and the plasma then separated, frozen, and thawed before incubation, the resulting mean increase in plasma renin activity from baseline values was 160%. We conclude that plasma from pregnant women should be handled at room temperature, or, if samples must be stored, they must be rapidly frozen, then thawed as rapidly as possible before incubation and assay if results are to be reproducible.
mesh_terms: D004789:Enzyme Activation; D005260:Female; D005615:Freezing; D006801:Humans; D011247:Pregnancy; D012083:Renin / Q000097:blood*; D013997:Time Factors
chemical_list: D012083:Renin