Inactivation of Renin Substrate by Soybean Trypsin Inhibitors: Implications for Measurement of Circulating Inactive Renin

In a new method for measurement of inactive rat plasma renin, the trypsin generated angiotensin I immunoreactive material, which was HPLC characterized as similar to tetradecapeptide renin substrate, is removed by a cation exchange resin before the renin incubation step. The method also corrects for trypsin destruction of endogenous angiotensinogen by the addition of exogenous angiotensinogen. When measured with this method inactive renin in rat plasma decreased after nephrectomy and increased after adrenalectomy. This is in accordance with findings in humans. A sexual dimorphism of prorenin (inactive renin) in rat plasma, similar to that reported in humans and mice, was demonstrated. Thus, inactive renin in the rat is no exception among species, and the rat might be a suitable animal model for further studies dealing with the physiology of prorenin in plasma and tissues.Key words: angiotensinogen, inactive renin, renin.

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Does heparin inhibit renin activity?

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y91-201 ◽

1991 ◽

Vol 69 (9) ◽

pp. 1360-1363 ◽

Cited By ~ 1

Author(s):

Masato Matsunaga ◽

Yoko Yamanaka ◽

Noriko Nagano ◽

Yuki Iwasaki ◽

Yumi Saito ◽

...

Keyword(s):

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Smooth Muscle Cell ◽

Muscle Cell ◽

Vascular Smooth Muscle Cell ◽

Plasma Renin ◽

Renin Activity ◽

Renin Substrate ◽

Significant Difference ◽

Inactive Renin

Although heparin was reported in the 1960s to inhibit renin activity, this has not always been confirmed by other investigators. Hence, we re-examined whether heparin really inhibits renin or not. Renin activities were determined by radioimmunoassay of angiotensin I generated at pH 7.4. (i) No significant difference was found between the two kinds of plasma samples obtained with heparin and with EDTA as anticoagulant, in ARC (renin activity with addition of sheep renin substrate), TRC (ARC after activation of inactive renin by trypsin), or PRA (plasma renin activity without additional substrate), (ii) Even in higher concentrations of heparin up to 500 U/mL, neither PRA, ARC, nor TRC of plasma was affected significantly. (iii) Heparin, in concentrations up to 500 U/mL, exerted no significant effect on TRC of the media of human vascular smooth muscle cell culture. In conclusion, heparin does not exert any significant inhibitory effect on human renin nor does it affect activation of inactive renin by trypsin in the range of concentration of practical use, under the conditions employed in this study.Key words: plasma renin, tissue renin, inactive renin, vascular smooth muscle cell, trypsin.

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Enzymatic Activity of Renin in Plasma of Normal and Uraemic Subjects

Clinical Science ◽

10.1042/cs0670365 ◽

1984 ◽

Vol 67 (3) ◽

pp. 365-368 ◽

Cited By ~ 3

Author(s):

Theodore A. Kotchen ◽

Tam T. Guyenne ◽

Pierre Corvol ◽

Joel Menard

Keyword(s):

Renal Failure ◽

Enzymatic Activity ◽

Plasma Renin ◽

Normal Subjects ◽

Renin Activity ◽

Angiotensin I ◽

Renin Substrate ◽

Inactive Renin ◽

Substrate Concentrations

1. Plasma renin reactivity (PRR) is the rate of angiotensin I production after addition of renin to plasma, minus endogenous renin activity. PRR is increased in plasma of patients with renal failure compared with that of normal subjects. The present study was carried out to determine if increased PRR in uraemic plasma is related to differences of endogenous active or inactive renin, endogenous renin substrate, or pH of the incubation in vitro. 2. PRR in plasma of ten uraemic patients was greater (P<0.02) than that in plasma of ten normal subjects in incubations carried out at pH 7.4 and 5.7. 3. Increased PRR was not accounted for by differences of endogenous active and inactive renin activity. 4. After addition of renin, renin concentration (measured by direct radioimmunoassay) did not differ in normal and uraemic plasma. 5. Renin substrate concentration, measured both indirectly and by direct radioimmunoassay, also did not differ in normal and uraemic plasma. 6. Increased PRR in uraemic plasma is not related to alterations of renin or renin substrate concentrations. These observations are consistent with our earlier hypothesis that there is a deficiency of a renin inhibitor in uraemic plasma.

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Effect of Age on the Renin-Angiotensin-Aldosterone System in Normal Subjects: Simultaneous Measurement of Active and Inactive Renin, Renin Substrate, and Aldosterone in Plasma

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem-62-2-384 ◽

1986 ◽

Vol 62 (2) ◽

pp. 384-389 ◽

Cited By ~ 95

Author(s):

KAZUO TZUNODA ◽

KEISHI ABE ◽

TOSHIKAZU GOTO ◽

MINORU YASUJIMA ◽

MAKITO SATO ◽

...

Keyword(s):

Simultaneous Measurement ◽

Normal Subjects ◽

Renin Substrate ◽

Renin Angiotensin Aldosterone System ◽

Renin Angiotensin ◽

Inactive Renin ◽

Effect Of Age

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Angiotensins I and II, active and inactive renin, renin substrate, renin activity, and angiotensinase in human liquor amnii and plasma

American Journal of Obstetrics and Gynecology ◽

10.1016/0002-9378(75)90463-9 ◽

1975 ◽

Vol 121 (5) ◽

pp. 626-630 ◽

Cited By ~ 132

Author(s):

S.L. Skinner ◽

Elizabeth J. Cran ◽

Robyn Gibson ◽

R. Taylor ◽

W.A.W. Walters ◽

...

Keyword(s):

Renin Activity ◽

Liquor Amnii ◽

Renin Substrate ◽

Inactive Renin

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Trypsin-Activatable Inactive Renin in Rat Plasma

Clinical Science ◽

10.1042/cs0640137 ◽

1983 ◽

Vol 64 (2) ◽

pp. 137-140 ◽

Cited By ~ 14

Author(s):

Nicola Glorioso ◽

Paolo Madeddu ◽

Paolo Dessi'-Fulgheri ◽

Giuseppe Fois ◽

Franca Meloni ◽

...

Keyword(s):

Rat Plasma ◽

Renin Activity ◽

Trypsin Activity ◽

Ph Optimum ◽

Renin Substrate ◽

Inactive Form ◽

Wide Range ◽

Maximal Activation ◽

Inactive Renin ◽

Range Of Variation

1. Activation of inactive renin in rat plasma has been studied with different trypsin concentrations and incubation times at pH 6.2 and 4°C. 2. Trypsin concentrations below 2 mg/ml, lower than endogenous rat plasma anti-trypsin activity, do not activate inactive renin, whereas maximal activation is obtained with trypsin at 6 mg/ml for 1 min at 4°C, pH 6.2. 3. Under these conditions trypsin can cleave dialysable fragments from renin substrate. ANG I can be generated at 37°C with a pH optimum of 5.3. Nevertheless, the ANG I formation at pH 6.2 was totally unaffected. 4. Incubations longer than 2 min with trypsin at 6 mg/ml can induce a direct cleavage of dialysable ANG I-containing fragments strongly interfering with the measurements of renin activity at pH 6.2. 5. On average 40% of the total renin measured in plasma of normotensive WK rats is in the inactive form, although a wide range of variation is observed.

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Trypsin activation of inactive renin: plasma blanks and angiotensin I radioimmunoassay

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y91-194 ◽

1991 ◽

Vol 69 (9) ◽

pp. 1315-1320 ◽

Cited By ~ 4

Author(s):

Jack D. Barrett ◽

Peter Eggena

Keyword(s):

Substrate Concentration ◽

Rat Plasma ◽

Direct Proportion ◽

Trypsin Treatment ◽

Angiotensin I ◽

Renin Substrate ◽

Active Renin ◽

Normal Plasma ◽

Inactive Renin ◽

Significant Bearing

Divergent conclusions exist as to whether inactive renin is present in nephrectomized rat plasma. A major factor contributing to this conflict may be related to significant changes in the "plasma blank" when trypsin-treated plasma is subjected to angiotensin I (AI) radioimmunoassay (RIA). In normal, but not nephrectomized rat plasma, AI-like substances are present in direct proportion to active renin. These substances are destroyed by trypsin. However, trypsin generates additional AI-like material, in both normal and nephrectomized rat plasma. This material, which is present in proportion to the renin substrate concentration, does not appear to be tetradecapeptide (TDP). In normal plasma, however, exogenous TDP is converted to AI in proportion to the active renin concentration and AI generation from TDP is increased by activation of inactive renin. However, in nephrectomized rat plasma, no AI generation from TDP was evident either before or after trypsin treatment. The coincident tryptic generation of a substance that quenches the levels of AI detected by RIA, combined with significant changes in the levels of endogenous and trypsin generated AI-like substances, may have significant bearing on the measured levels of inactive renin.Key words: prorenin, nephrectomy, angiotensin I radioimmunoassay, rat, plasma blanks.

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