Abstract
An inactive large molecular form of renin which can be acid and cryoactivated has been described in human amniotic fluid and plasma. The present study was conducted to determine whether the concentration of inactive renin is high in the newborn at a time when circulating active renin levels are known to be elevated, and whether inactive newborn renin can be separated from active renin by chromatography. 78 samples of newborn plasma were acidified to ph 5.5-5.7, the optimal ph for generating angiotensin I (angio I) from active renin, and treated with Bal and 8-OH quinoline to prevent formation of angiotensin 2. The samples were divided into 2 equal parts, one control for circulating angio I and one generated to angio I at 37°C for 1 hr prior to RIA. The control and generated samples were placed in an ice bath (3-4°C) for 10 hrs. The control samples contained 6.7 ± 1.0 ng/ml/hr (M and SEM) of active renin, and 14.1 ± 1.8 of cryoactivated renin (as PRA). The (37°C, 1 hr) generated samples contained 22.8 ± 1.3 ng/ml/hr of active renin and 17.7 ± 1.7 of cryoactivated renin (as PRA). Chromatography on 1M G-75 Sephadex columns eluted with 0.1M Na Phosphate buffer, ph 6.9 showed active renin in one fraction, M.W. 45,000, and cryoactivated and acid activated (ph 3.0) renin in another fraction, M.W. 67,000.
Conclusions: a) active and inactive renin are both in high concentration in newborn plasma, b) cryoactivated and acid activated renin are of similar M.W. and larger than active renin.
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Siegel, S., Hadeed, A. 1104 CRYOACTIVATION AND ACID ACTIVATION OF AN INACTIVE RENIN IN THE NEWBORN INFANT. Pediatr Res 12 (Suppl 4), 548 (1978). https://doi.org/10.1203/00006450-197804001-01110
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DOI: https://doi.org/10.1203/00006450-197804001-01110