Effects of pregnancy, oral contraception, and binephrectomy, on human plasma "prorenin" and its activator(s).
We compared two temperatures for cryoactivation, -4 degrees and 4 degrees C, in subjects representing high and low renin states. The colder temperature was universally more effective for activating prorenin, but not to the same degree in men and women, in all physiological states. At 4 degrees, for short intervals, false negatives are more likely to be obtained, especially in women and anephrics. We confirmed higher plasma renin activities (PRA) in women on oral contraceptive medication (pill), and in the 1st and 3rd trimester of pregnancy. The highest prorenin component was in the 1st trimester, the lowest in anephric subjects (2NX, about 28% of normal). Prorenin as percent of total renin was relatively constant in healthy men, women (no pill), women (pill), and women, 1st trimester. In the 3rd trimester, this percentage dropped, p less than 0.025; in anephric men and women, it rose (N.S.), suggesting highest prorenin convertase activity exists in the 3rd trimester, lowest activity in 2NX. This was confirmed by adding Trasylol during cryoactivation at -4 degrees C, and noting least, and greatest inhibition of prorenin activation, respectively. The effectiveness of trypsin relative to cold activation rises as the proportion of 2NX plasma increases in a mixture with normal plasma. The 2NX plasma lacks both prorenin, and its convertase. Trypsin can substitute for part of the convertase, and is therefore more effective than cold, which is rate-limited by convertase deficiency. Thus, the choice between trypsin and cold depends, in part, on whether only prorenin, or also its convertase, is being evaluated. Systemic convertase appears to be a dynamic physiological variable influencing renin production from prorenin, and is conditioned by the presence of healthy kidneys, and by sex hormones.
D000293:Adolescent; D000328:Adult; D003080:Cold Temperature; D003276:Contraceptives, Oral; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000097:blood*; D005260:Female; D006801:Humans; D007700:Kinetics; D009392:Nephrectomy; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011263:Pregnancy Trimester, Third; D012083:Renin / Q000097:blood*
D003276:Contraceptives, Oral; D004792:Enzyme Precursors; D012083:Renin