Plasma Renin Activity in Normal Human Pregnancy and in Pregnancy-Associated Hypertension, with Reference to Cryoactivation

1980 ◽  
Vol 59 (1) ◽  
pp. 49-53 ◽  
Author(s):  
E. D. M. Gallery ◽  
G. S. Stokes ◽  
A. Z. Györy ◽  
J. Rowe ◽  
J. Williams
Keyword(s):  
Plasma Renin Activity ◽  
Pregnant Women ◽  
Sodium Intake ◽  
Plasma Renin ◽  
Normal Pregnancy ◽  
Renin Activity ◽  
Central Feature ◽  
Plasma Renin Concentration ◽  
Significant Difference ◽  
In Pregnancy

1. Because hypertension is the central feature of pre-eclampsia, and because plasma renin activity is known to be elevated in normal pregnancy (with conflicting results published for pre-eclampsia), a prospective study of plasma renin activity was conducted in pregnancy, under conditions of a fixed sodium intake, in 178 initially normotensive volunteer subjects. Thirty of these women developed pregnancy-associated hypertension (pre-eclampsia) in the third trimester. 2. There was a significant elevation of plasma renin activity from the published values for non-pregnant women, throughout gestation in normotensive women. There was no significant difference, at any stage of gestation, between the values for normal women and those who developed pregnancy-associated hypertension. 3. The extent of cryoactivation of renin, produced by usual collection procedures, was investigated in a subgroup of the total population. It was highly significant and quite variable, but was similar in those who developed pregnancy-associated hypertension and in normal pregnant women. The mean increase in plasma renin concentration in maximally cryoactivated samples was 16-fold. 4. Neither measurement of peripheral plasma renin activity nor of cryoactivatable plasma renin concentration is of value in distinguishing between normal pregnant women and those destined for, or with pregnancy-associated, hypertension.

Renal sodium handling in normal humans subjected to low, normal, and extremely high sodium supplies

1985 ◽  
Vol 249 (6) ◽  
pp. F941-F947 ◽  
Author(s):  
J. C. Roos ◽  
H. A. Koomans ◽  
E. J. Dorhout Mees ◽  
I. M. Delawi
Keyword(s):  
Blood Pressure ◽  
Plasma Renin Activity ◽  
Sodium Intake ◽  
Extracellular Fluid ◽  
Plasma Renin ◽  
Renin Activity ◽  
Sodium Reabsorption ◽  
Lithium Clearance ◽  
Renal Sodium Handling ◽  
Sodium Handling

We studied renal sodium handling, extracellular fluid volume (ECFV), plasma renin activity, aldosterone and norepinephrine, and blood pressure in eight healthy volunteers after equilibration on intakes of 20, 200, and 1,128 +/- 141 meq sodium, respectively. Renal sodium handling was assessed by means of clearance studies during maximal water diuresis and lithium clearance. Urinary sodium excretions were 22 +/- 4, 202 +/- 19, and 1,052 +/- 86 meq/day. From the lower to the upper sodium intake level, 24-h creatinine clearance rose from 111 +/- 7 to 136 +/- 11 ml/min and inulin clearance from 103 +/- 9 to 129 +/- 9 ml/min, whereas proximal and distal fractional sodium reabsorption (FSRprox and FSRdist, respectively) fell from 86.8 +/- 1.3 to 79.0 +/- 2.7% and from 96.5 +/- 0.5 to 76.0 +/- 1.9%, respectively. During the normal sodium intake (200 meq), intermediate values were recorded. The changes in fractional lithium clearance were less consistent but correlated with FSRprox (r = 0.78, P less than 0.001) and not with FSRdist. Major changes in plasma renin activity, aldosterone, and, to a lesser extent, norepinephrine accompanied these changes in kidney function, displaying inverse and exponential correlations with daily sodium excretion and ECFV. No consistent rise in blood pressure was detected. These observations indicate that in healthy humans renal adaptation to vast variations in sodium intake includes resetting of glomerular filtration rate, FSRprox, and, in particular, FSRdist. Alterations in neurohumoral factors may play a dominant role in this adaptation.

Cold Promoted Activation of Factor VII(CPA) and Plasma Renin Activity (PRA)

1979 ◽  
Author(s):  
E. van Royen ◽  
K. Hoekman ◽  
P. Elte ◽  
A. Schellekens
Keyword(s):  
Plasma Renin Activity ◽  
Pregnant Women ◽  
Plasma Renin ◽  
Special Care ◽  
Renin Activity ◽  
Factor Vii ◽  
Plasma Samples ◽  
Spontaneous Activation ◽  
Esterase Inhibitor

The CPA phenomenon occurs in about 20% of the population, 60% of women using contraceptive drugs and 90% of pregnant women. Cpa positive plasma samples show at 4°C spontaneous activation of prekallikrein and factor VII, shortening of the ThrombotestR Time (TT) and consumption of C4 esterase inhibitor. Since kalllkrein may activate prorenin, we related the CPA phenomenon to PRA.A highly significant correlation was found between the shortening of the TT at 4°C and an increase in PRA during storage of random plasma samples.It is concluded that special care should be taken when PRA is determined in CPA positive plasma samples in order to avoid erroneously high PRA levels.

Plasma renin activity and plasma prorenin assays

1991 ◽  
Vol 37 (10) ◽  
pp. 1811-1819 ◽  
Author(s):  
J E Sealey
Keyword(s):  
Plasma Renin Activity ◽  
Sodium Intake ◽  
Vascular Complications ◽  
Plasma Renin ◽  
Renin Activity ◽  
Blood Collection ◽  
Kinetic Assay ◽  
Renin Substrate ◽  
Patients With Diabetes ◽  
Commercial Kits

Abstract Sensitivity and accuracy are essential features of an assay of plasma renin activity (PRA) because the normal concentration of PRA is only 1 pmol/L, and subnormal concentrations have diagnostic relevance. Conditions for blood collection need to be standardized but the conditions are not difficult for outpatients. For routine diagnostic purposes blood should be collected from ambulatory (ideally, untreated) patients on moderate sodium intake. To avoid irreversible cryoactivation of plasma prorenin (which is present in 10-fold greater concentrations than renin), samples should be processed at room temperature and stored completely frozen. Cryoactivation occurs when plasma is liquid at temperatures less than 6 degrees C. PRA is commonly measured with an enzyme kinetic assay in which angiotensin I (Ang I) is formed by the reaction of plasma renin with endogenous renin substrate (angiotensinogen). The Ang I so formed is measured by RIA; results are expressed as an hourly rate (micrograms/L formed per hour). This method, which is provided by most commercial kits, has the potential for unlimited sensitivity because the step for Ang I generation can be prolonged as long as necessary, so that enough Ang I forms to be measured accurately. Unfortunately, that sensitivity is not always exploited. Dilution of plasma during pH adjustment should be kept to a minimum. The Ang I generation step should last at least 3 h. The step should last 18 h for samples with PRA less than 1.0 micrograms/L per hour, to eliminate the errors inherent in the measurement and subtraction of immunoreactive Ang I in the untreated plasma (blank subtraction). These changes actually simplify PRA measurements because they eliminate the need for ice in the clinic and reduce by almost half the number of samples to be assayed by RIA. I also describe the method for measurement of plasma prorenin, which may be an important marker for patients with diabetes mellitus who subsequently develop vascular complications.

Cryoactivation of renin in plasma from pregnant and nonpregnant subjects, and its control.

1979 ◽  
Vol 25 (11) ◽  
pp. 1972-1974 ◽  
Author(s):  
J Rowe ◽  
E D Gallery ◽  
A Z Györy
Keyword(s):  
Plasma Renin Activity ◽  
Pregnant Women ◽  
Room Temperature ◽  
Plasma Renin ◽  
Renin Activity ◽  
Baseline Values

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.

DIURNAL VARIATIONS OF PLASMA ALDOSTERONE IN SUPINE MAN: RELATIONSHIP TO PLASMA RENIN ACTIVITY AND PLASMA CORTISOL

1975 ◽  
Vol 80 (1) ◽  
pp. 95-103 ◽  
Author(s):  
Helmut Armbruster ◽  
Wilhelm Vetter ◽  
Rainer Beckerhoff ◽  
Jürg Nussberger ◽  
Hans Vetter ◽  
...  
Keyword(s):  
Plasma Renin Activity ◽  
Plasma Cortisol ◽  
Sodium Intake ◽  
Plasma Concentrations ◽  
Renin Angiotensin System ◽  
Plasma Renin ◽  
Plasma Aldosterone ◽  
Renin Activity ◽  
Dominant Factor ◽  
Sodium Restriction

ABSTRACT In order to investigate the role of renin secretion and of ACTH on the circadian rhythm of plasma aldosterone (PA), plasma renin activity (PRA), plasma cortisol (PC) and PA were determined at short-time intervals in 10 normal supine men. Six subjects were studied under a normal sodium intake and 4 under sodium restriction. In 4 subjects the secretion of ACTH was suppressed by dexamethasone. Under normal sodium intake changes in PA seemed to be more in parallel with changes in PC than by those in PRA as indicated by a higher significant correlation between PA and PC than between PA and PRA in 3 of the 4 subjects. In 1 subject no correlation was observed between PA and PC despite visual synchronism between the plasma concentrations of both hormones. Under dexamethasone medication fluctuations in PA were followed by those in PRA while PC was less than 2 μg/100 ml. In the sodium restricted state, changes in PA were closely paralleled and significantly correlated to PRA while no correlation was seen between PA and PC. Under dexamethasone medication the significant correlation between PA and PRA persisted. Our results indicate that in normal supine man the influence of ACTH and renin on PA may vary with different sodium intakes. Under normal sodium intake ACTH seems to be the dominant factor controlling PA, whereas under sodium restriction changes in PA are mediated through the renin angiotensin system. When the secretion of ACTH is suppressed by dexamethasone, renin controls PA both under normal and low sodium intake.

scholarly journals Muscle sympathetic nerve activity and volume-regulating factors in healthy pregnant and nonpregnant women

2017 ◽  
Vol 313 (4) ◽  
pp. H782-H787 ◽  
Author(s):  
Nisha Charkoudian ◽  
Charlotte W. Usselman ◽  
Rachel J. Skow ◽  
Jeffery S. Staab ◽  
Colleen G. Julian ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Plasma Renin Activity ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Plasma Osmolality ◽  
Plasma Renin ◽  
Renin Activity ◽  
Pressure Regulation ◽  
Nerve Activity ◽  
In Pregnancy

Healthy, normotensive human pregnancies are associated with striking increases in both plasma volume and vascular sympathetic nerve activity (SNA). In nonpregnant humans, volume-regulatory factors including plasma osmolality, vasopressin, and the renin-angiotensin-aldosterone system have important modulatory effects on control of sympathetic outflow. We hypothesized that pregnancy would be associated with changes in the relationships between SNA (measured as muscle SNA) and volume-regulating factors, including plasma osmolality, plasma renin activity, and arginine vasopressin (AVP). We studied 46 healthy, normotensive young women (23 pregnant and 23 nonpregnant). We measured SNA, arterial pressure, plasma osmolality, plasma renin activity, AVP, and other volume-regulatory factors in resting, semirecumbent posture. Pregnant women had significantly higher resting SNA (38 ± 12 vs. 23 ± 6 bursts/min in nonpregnant women), lower osmolality, and higher plasma renin activity and aldosterone (all P < 0.05). Group mean values for AVP were not different between groups [4.64 ± 2.57 (nonpregnant) vs. 5.17 ± 2.03 (pregnant), P > 0.05]. However, regression analysis detected a significant relationship between individual values for SNA and AVP in pregnant ( r = 0.71, P < 0.05) but not nonpregnant women ( r = 0.04). No relationships were found for other variables. These data suggest that the link between AVP release and resting SNA becomes stronger in pregnancy, which may contribute importantly to blood pressure regulation in healthy women during pregnancy. NEW & NOTEWORTHY Sympathetic nerve activity and blood volume are both elevated during pregnancy, but blood pressure is usually normal. Here, we identified a relationship between vasopressin and sympathetic nerve activity in pregnant but not nonpregnant women. This may provide mechanistic insights into blood pressure regulation in normal pregnancy and in pregnancy-related hypertension.

Effect of nitric oxide synthase inhibition on cardiovascular and hormonal regulation during pregnancy in the rat

2000 ◽  
Vol 78 (5) ◽  
pp. 423-427 ◽  
Author(s):  
Yunlong Zhang ◽  
Susan Kaufman
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Plasma Renin Activity ◽  
Plasma Volume ◽  
Atrial Natriuretic Factor ◽  
Plasma Renin ◽  
Renin Activity ◽  
Pregnant Rats ◽  
Oxide Synthase ◽  
In Pregnancy

Recent studies have shown that nitric oxide (NO) biosynthesis increases in pregnancy and that inhibition of nitric oxide synthase (NOS) induces some pathological processes characteristic of preeclampsia. The current project sought to study the effect of the NOS inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 10 µg·min-1, sc for 7 days) on plasma volume, plasma atrial natriuretic factor (ANF), plasma endothelin-1 (ET), and plasma renin activity (PRA) during gestation in conscious rats. NOS inhibition caused mean arterial pressure to increase in both virgin and 21-day pregnant rats. Plasma volume fell in the pregnant rats [L-NAME, 4.5 ± 0.3 mL·100 g-1 body wt. (n = 7) vs. D-NAME, 6.8 ± 0.2 mL·100 g-1 body wt. (n = 10); P < 0.05] but not in the virgin rats [L-NAME, 4.3 ± 0.1 mL·100 g-1 body wt. (n = 6) vs. D-NAME, 4.8 ± 0.2 mL·100 g-1 body wt. (n = 8)]. There was no effect of NOS inhibition on plasma ANF levels or PRA in either the virgin or pregnant rats. However, L-NAME did decrease plasma ET levels in the pregnant rats [L-NAME, 19.6 ± 1.6 pg·mL-1 (n = 8) vs. D-NAME, 11.6 ± 2.5 pg·mL-1 (n = 9); P < 0.05]. Our results confirm that NO is involved in cardiovascular homeostasis in pregnancy; NOS inhibition selectively reduces plasma volume in pregnant rats, thus mimicking a major pathophysiological perturbation of preeclampsia. However, it does not induce the hormonal changes characteristic of preeclampsia, namely the decrease in PRA and increase in plasma ET and ANF levels. Key words: plasma volume, preeclampsia, endothelin, atrial natriuretic factor, plasma renin activity.

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