Renal reserve during human pregnancy

1996 ◽  
Vol 271 (1) ◽  
pp. F16-F20 ◽  
Author(s):  
S. N. Sturgiss ◽  
R. Wilkinson ◽  
J. M. Davison
Keyword(s):  
Glomerular Filtration Rate ◽  
Amino Acid ◽  
Filtration Rate ◽  
Renal Plasma Flow ◽  
Late Pregnancy ◽  
Normal Pregnancy ◽  
Acid Infusion ◽  
Amino Acid Infusion ◽  
Control Infusion ◽  
Healthy Females

Pregnancy in healthy women is associated with increments in glomerular filtration rate (GFR) and effective renal plasma flow (ERPF). We hypothesized that the hyperfiltration of normal pregnancy attenuates or exhausts renal reserve. In 21 healthy females studied serially in early and late pregnancy and then on average 15 wk postpartum, GFR and ERPF were determined by inulin and p-aminohippurate clearances, respectively, before and during either an amino acid infusion (Vamin 9; Kabi Pharmacia) (n = 14) or a control infusion of Hartman's solution (n = 7), both infused at 4 ml/min for 210 min. In early and late pregnancy, GFR increased significantly in response to amino acid infusion [from 137 +/- 29 to 162 +/- 35 ml/min (P < 0.001) and from 134 +/- 29 to 148 +/- 40 ml/min (P < 0.01), respectively], with the increments (18 and 10%, respectively) not significantly different from postpartum (non-pregnant) when GFR increased by 12% from 94 +/- 22 to 105 +/- 23 ml/min (P < 0.002). Amino acid infusion significantly increased ERPF from 874 +/- 188 to 980 +/- 215 ml/min in early pregnancy (P < 0.01), from 684 +/- 135 to 773 +/- 181 ml/min in late pregnancy (P < 0.01), and from 507 +/- 121 to 560 +/- 141 ml/min postpartum (P < 0.006), increments of 12, 13, and 10%, respectively. GFR did not change in response to control infusion. We conclude that, despite gestational increments in renal hemodynamics of > 40%, pregnancy does not attenuate the renal response to amino acid infusion.

Glomerular heteroporous membrane modeling in third trimester and postpartum before and during amino acid infusion

2002 ◽  
Vol 282 (1) ◽  
pp. F170-F175 ◽  
Author(s):  
J. E. C. Milne ◽  
M. D. Lindheimer ◽  
J. M. Davison
Keyword(s):  
Amino Acid ◽  
Renal Plasma Flow ◽  
Late Pregnancy ◽  
Third Trimester ◽  
Acid Infusion ◽  
Amino Acid Infusion ◽  
Protein Excretion ◽  
Membrane Modeling ◽  
Additional Amino Acid ◽  
Baseline State

Human pregnancy is associated with substantial increments in glomerular filtration rate (GFR) and renal plasma flow (RPF). We have previously demonstrated that permselectivity to neutral dextrans is altered in pregnancy, theoretical analysis of the dextran sieving curves suggesting that elevated GFR is due to increased RPF and decreased glomerular oncotic pressure (πGC) with no evidence of increased transglomerular hydrostatic pressure difference (ΔP). These conclusions have been challenged, with claims that the rise in GFR is primarily a result of a decrement in πGC. With refined laboratory and infusion protocols, we have reexplored the determinants of ultrafiltration in a serial study of 11 healthy women in late pregnancy (LP) and 4 mo postpartum (PP), both in the baseline state and after increasing GFR and RPF by infusion of amino acids. Results were analyzed using two computer modeling programs. Increased GFR in LP (38%, P < 0.05) was due to a combination of elevated RPF (22%) and a decrement in πGC and associated with an increased ultrafiltration coefficient, without evidence of increased ΔP, and additional amino acid-provoked GFR increments ( P < 0.05) produced similar findings. In addition, refined methodology permitted collection of sufficient data on excreted large-radii dextrans (>60 Å) to better define the nondiscriminatory “shunt” pathway (ω0) and the standard deviation of pore size ( S) about the mean radius of the distribution. Thus it was possible to demonstrate that the physiological increase in total protein excretion in LP is associated with a prominent shunt and an upward shift in breadth of distribution of pore sizes. This ability to quantify ω0 and S will now permit better evaluation of the pathophysiological changes in the glomerulus associated with pregnancy in women with renal disease and in gravidas developing preeclampsia.

Enhanced Glomerulopressin Production and Glomerular Filtration Rate by Amino Acid Infusion in Normal Humans

1991 ◽  
Vol 196 (2) ◽  
pp. 170-174 ◽  
Author(s):  
E. Maggiora ◽  
C. Silberstein ◽  
E. Arany ◽  
J. C. Salvidea ◽  
E. D. Castillo ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Amino Acid ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Acid Infusion ◽  
Amino Acid Infusion ◽  
Normal Humans

Renal disease in pregnancy

1989 ◽  
Vol 1 (2) ◽  
pp. 177-192 ◽  
Author(s):  
Priscilla Kincaid-Smith ◽  
Kenneth Fairley
Keyword(s):  
Glomerular Filtration Rate ◽  
Filtration Rate ◽  
Renal Plasma Flow ◽  
First Trimester ◽  
Normal Pregnancy ◽  
Intimate Relationship ◽  
Physiological Changes ◽  
Anatomical Changes ◽  
The Right ◽  
In Pregnancy

There is an intimate relationship between the kidney and pregnancy. Renal plasma flow increases by 50–70% during a normal pregnancy and the glomerular filtration rate by about 50%.1These changes commence in the first trimester and fall in the last trimester reaching normal levels within about four weeks postpartum. These physiological changes are accompanied by striking anatomical changes which consist of dilatation of the ureter, pelvis and calyces, together with an increase in renal parenchymal size. The dilatation i s more marked on the right and may appear in the first trimester. At term, 90% of pregnant women show this change.2

scholarly journals Nitric oxide: a potential mediator of amino acid-induced renal hyperemia and hyperfiltration.

1991 ◽  
Vol 1 (12) ◽  
pp. 1271-1277
Author(s):  
A J King ◽  
J L Troy ◽  
S Anderson ◽  
J R Neuringer ◽  
M Gunning ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Glomerular Filtration Rate ◽  
Amino Acid ◽  
Glomerular Filtration ◽  
Plasma Flow ◽  
Filtration Rate ◽  
Renal Plasma Flow ◽  
Competitive Inhibitor ◽  
Arterial Blood

The role of nitric oxide in the modulation of systemic and renal hemodynamics was examined by using N omega-monomethyl-L-arginine (L-NMMA, 110 micrograms/kg/min), a competitive inhibitor of the conversion of L-arginine to nitric oxide. L-NMMA or saline vehicle (9.6 microL/min) was infused intravenously into anesthetized euvolemic Munich-Wistar rats. After 30 min, L-NMMA resulted in a uniform increase in mean arterial blood pressure (111 +/- 1 to 128 +/- 2 mmHg; P less than 0.05) and a modest reduction in renal plasma flow rate (4.4 +/- 0.2 to 4.2 +/- 0.1 mL/min; P less than 0.05), without change in glomerular filtration rate (1.16 +/- 0.03 to 1.15 +/- 0.03 mL/min); vehicle had no effect on these renal parameters. These rats were then subdivided to receive an intravenous infusion (37 microL/min) of either 10% glycine, 11.4% mixed amino acids, or equiosmolar dextrose. L-NMMA pretreatment markedly attenuated glycine-induced hyperfiltration (10 +/- 6 versus 33 +/- 5%, L-NMMA versus vehicle; P less than 0.05) and obliterated the renal hyperemic response (-7 +/- 6 versus 16 +/- 4%, L-NMMA versus vehicle; P less than 0.05). L-NMMA also caused modest blunting of the mixed amino acid-induced hyperfiltration (18 +/- 4 versus 30 +/- 4%, L-NMMA versus vehicle; P = 0.056) but failed to curtail the renal hyperemia (16 +/- 6 versus 20 +/- 4%). Dextrose had no effect on glomerular filtration rate or renal plasma flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Captopril augments the renal response to an amino acid infusion in diabetic adults

1988 ◽  
Vol 255 (4) ◽  
pp. F755-F762 ◽  
Author(s):  
L. A. Slomowitz ◽  
R. Hirschberg ◽  
J. D. Kopple
Keyword(s):  
Amino Acid ◽  
Enzyme Inhibitor ◽  
Renal Plasma Flow ◽  
Dependent Diabetes Mellitus ◽  
Diabetic Patients ◽  
Base Line ◽  
Maximum Increase ◽  
Acid Infusion ◽  
Amino Acid Infusion ◽  
Group 3

This study examined whether patients with insulin-dependent diabetes mellitus and normal renal function have an altered response to an amino acid infusion when they are pretreated with a converting-enzyme inhibitor. Three groups of adults received amino acid infusions for 20 min on two occasions separated by a 240-min interval. Groups 1 (6 normals) and 2 (6 diabetics) ingested captopril (12.5 mg) 120 min before starting the second infusion. Group 3 (4 diabetics) did not receive captopril. Diabetics had normal base-line renal plasma flow, as indicated by para-aminohippuric acid clearance (CPAH), and glomerular filtration rate (GFR). In group 1, the maximum increase in CPAH was significant and similar with both infusions, 23 +/- 5 vs. 15 +/- 3% (SE); maximal changes in GFR were also significant and similar, 20 +/- 5 vs. 20 +/- 6%. In Group 2, the maximal increase in CPAH and GFR with the first infusion was 28 +/- 7 and 23 +/- 6%, respectively. After captopril, the increases in CPAH and GFR were significantly greater than with the first infusion (64 +/- 8%, P less than 0.002, and 67 +/- 9%, P less than 0.002, respectively). In Group 3 diabetics, there was no difference in either CPAH or GFR with the first vs. the second infusion. Thus captopril enhances the renal hemodynamic response to an amino acid load in diabetic patients but not in normal adults.

Effects of late pregnancy and early lactation on renal urea handling in Corriedale ewes

1998 ◽  
Vol 130 (2) ◽  
pp. 213-216 ◽  
Author(s):  
B. B. NDIBUALONJI ◽  
M.-N. RODRIGUEZ ◽  
D. DEHARENG ◽  
A. CIRIO ◽  
J.-M. GODEAU
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Plasma Flow ◽  
Filtration Rate ◽  
Renal Plasma Flow ◽  
Late Pregnancy ◽  
Fractional Excretion ◽  
Urine Osmolality ◽  
Early Lactation ◽  
Plasma Urea

The aim of the study was to investigate the changes in renal function in late pregnant and early lactating Corriedale ewes. Compared with the non-productive state, plasma urea concentration was increased by 67% during pregnancy, whereas it decreased by 36% during lactation. Urine flow, urea clearance, renal plasma flow and glomerular filtration rate were significantly reduced (P<0·05) during both late pregnancy and early lactation. Filtered load of urea and the amount of urea eliminated were significantly reduced (P<0·05) only in lactating ewes. No changes were noted in the fractional excretion of urea, the filtration fraction and the urine osmolality during both late pregnancy and early lactation. It was concluded that, as in other breeds, Corriedale ewes can adapt to increased nitrogen requirements during late pregnancy, and especially during early lactation, by increasing the renal conservation of urea. Unlike other breeds, however, Corriedale ewes restrict the urine urea losses mainly by reducing renal plasma flow and glomerular filtration rate, without any modification of the tubular reabsorption of urea during both late pregnancy and early lactation.

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