Lower Effective Renal Plasma Flow Research Articles

Central Body Fat Distribution Associates with Unfavorable Renal Hemodynamics Independent of Body Mass Index

Central distribution of body fat is associated with a higher risk of renal disease, but whether it is the distribution pattern or the overall excess weight that underlies this association is not well understood. Here, we studied the association between waist-to-hip ratio (WHR), which reflects central adiposity, and renal hemodynamics in 315 healthy persons with a mean body mass index (BMI) of 24.9 kg/m(2) and a mean (125)I-iothalamate GFR of 109 ml/min per 1.73 m(2). In multivariate analyses, WHR was associated with lower GFR, lower effective renal plasma flow, and higher filtration fraction, even after adjustment for sex, age, mean arterial pressure, and BMI. Multivariate models produced similar results regardless of whether the hemodynamic measures were indexed to body surface area. Thus, these results suggest that central body fat distribution, independent of BMI, is associated with an unfavorable pattern of renal hemodynamic measures that could underlie the increased renal risk reported in observational studies.

Renal Function after Preeclampsia: A Longitudinal Pilot Study

Background: Women with a history of preeclampsia are at increased risk to develop end-stage renal disease. In this longitudinal study, we evaluated renal function in women with a history of severe preeclampsia and parous controls over a period of 14 years. Methods: Renal function was measured 1 and then 14 years postpartum by para-aminohippurate and inulin clearances in 20 women with a history of severe preeclampsia and 8 parous controls. Results: The difference in glomerular filtration rate 1 year postpartum between women with a history of preeclampsia and parous controls (112 ± 10 and 125 ± 8 ml/min/1.73 m², p < 0.01) had disappeared 14 years postpartum (104 ± 10 and 109 ± 13 ml/min/1.73 m², p = 0.37). There was a consistent trend for a lower effective renal plasma flow both 1 and 14 years postpartum (477 ± 90 and 543 ± 92, p = 0.09 and 473 ± 85 and 543 ± 98 ml/min/1.73 m², p = 0.07). Conclusions: This explorative study suggests no accelerated renal function loss in the first decade after preeclampsia.

The prognostic value of relative renal function greater than 51% in the pelvi-ureteric junction-obstructed kidney on 99mtechnetium mercaptoacetyltriglycine study

Objective Obstructed kidneys with relative function (RRF) estimates >50% are occasionally noted in 99mtechnetium mercaptoacetyltriglycine renal studies. It is thought that increased RRF might confer some benefit and/or permit delayed intervention. We compared the RRF and absolute renal function, as defined by effective renal plasma flow (ERPF), of obstructed kidneys in the ranges >51%, 40%–50% and <40% RRF before and after pyeloplasty. Methods Twenty children, median age 13.5 months (range 3 weeks–126 months), satisfied criteria for the diagnosis of PUJ obstruction and estimated function >51% (group 1). Their pre- and post-intervention data were compared with 21 children, median age 2 months (range 1 week–126 months), with PUJ obstruction and 40%–50% RRF (group 2); and 21, median age 6 months (range two days–110 months), with RRF below 40% (group 3). Kidneys showing signs of continuing obstruction after surgery were excluded. Results Final ERPF was negatively related to age: younger children, and those with a higher preoperative ERPF, recovered better than older children and those with a lower ERPF ( p < 0.05). Pre- and postoperative mean ERPF in group 1 was 76 (range 21–203) and 102 (6–240) ml/min/1.73 msq respectively. In group 2, these values were 75.2 (30–187) and 130.9 (44–306) ml/min/1.73 msq, and they were 42.6 (5–179) and 80.2 (17–205) ml/min/1.73 msq in group 3. When adjustment was made for preoperative ERPF, there was no evidence that RRF grouping was related to ERPF outcome. The postoperative ERPF of seven of 20 kidneys from group 1 (>51%) was lower than the ERPF before surgery compared to 2/21 in group 2 and 4/21 in group 3, but these differences were not statistically significant ( p = 0.25). Conclusions Most kidneys in each functional range improved when obstruction was relieved. An RRF >51% in the obstructed kidney was not always prognostically beneficial, and may be a warning of impending decompensation in a minority.

Anaemia in chronic heart failure is not only related to impaired renal perfusion and blunted erythropoietin production, but to fluid retention as well

Anaemia is prevalent in the chronic heart failure (CHF) population, but its cause is often unknown. The present study aims to investigate the relation between anaemia, renal perfusion, erythropoietin production, and fluid retention in CHF patients. We studied 97 patients with CHF, of which 15 had anaemia (Hb<13.0 g/dL in men and Hb<12.0 g/dL in women), without haematinic deficiencies. Glomerular filtration rate (GFR) and extracellular volume (ECV) were measured as the clearance and the distribution volume of constantly infused 125I-iothalamate, respectively. Effective renal plasma flow (ERPF) was determined as the clearance of 131I-hippuran. Anaemic CHF patients displayed significantly reduced GFR (P=0.002), ERPF (P=0.005) and EPO production (P=0.001), and an elevated ECV (P=0.015). Multivariable analysis demonstrated that lower GFR (P=0.003), lower ERPF (P=0.004), lower EPO production (P=0.006), and a higher ECV (P=0.001) were significant independent predictors of lower haemoglobin levels. Anaemia in CHF is not only independently associated with impaired renal perfusion and blunted EPO production, but to fluid retention as well.

Genetic contribution to the acute effects of angiotensin II type 1 receptor blockade

Clinical observations point towards heterogeneity in patients' responses to antihypertensive drugs. As our earlier work showed that angiotensin II (AngII) sensitivity is associated with the A1166C polymorphism of the AngII type 1 receptor (AT1R) gene, we conducted the present study in which the responses to acute AT1R blockade were evaluated. After 7 days of low and high sodium diet, the hormonal as well as systemic and renal hemodynamic responses to acute AT1R blockade with EXP3174 (active metabolite of losartan) were studied in 15 AA and 14 CC essential hypertensive patients. By means of platelet-binding studies the baseline AT1R density (Bmax) and affinity (KD) was tested. During low and high salt diet, baseline Bmax and KD were comparable between both genotype groups. At baseline, during low salt diet, CC patients had significantly lower glomerular filtration rate and a trend towards lower effective renal plasma flow (ERPF) compared to AA patients. Blood pressure responses to EXP3174 during high salt were significantly blunted in CC patients compared to AA patients (mean arterial pressure: 1.8 versus 7.5%; P < 0.05). During low salt the increase in ERPF (12.9 versus 16.1%; P = 0.08), as well as the decrease in filtration fraction (9.0 versus 14.0%; P = 0.05) and renal vascular resistance (7.5 versus 15.1%; P = 0.06) were blunted in CC patients compared to AA patients. Humoral effects did not differ between the groups. This study shows that the systemic and renal hemodynamic responses to acute AT1R blockade are, at least in part, genetically determined.

Serum Uric Acid Levels in Patients With Cirrhosis: A Reevaluation

It has been reported that the serum uric acid levels in patients with cirrhosis were decreased compared with healthy subjects. These studies suggested that the lower serum uric acid levels in cirrhotic patients were attributed mainly to an increased effective vascular volume, and consequently to an excessive renal clearance of uric acid. However, the previous observations are challenged by a recent hypothesis for the pathogenesis of hyperdynamic circulation and formation of ascites in cirrhosis. The current study was undertaken to reevaluate serum uric acid levels in patients with cirrhosis. Ninety-eight cirrhotic patients with normal renal functions were included in this study. All biochemical and hemodynamic data were utilized for analysis. The mean serum uric acid level (mean, 6.1+/-1.2 mg/dL; range, 2.7-9.1 mg/dL) was higher than that of the age- and sex-matched healthy control subjects (mean, 5.5+/-1.3 mg/dL; range, 2.9-8.1 mg/dL; p = 0.018). Using multiple regression analysis it was determined that the serum uric acid level was not related to the severity of liver disease, cardiac index, systemic vascular resistance, and hepatic venous pressure gradient but was related closely to age (r = 0.210, p = 0.026) and effective renal plasma flow (r = -0.677, p < 0.0001). Compared with cirrhotic patients without ascites, those with ascites had a significantly higher serum uric acid level (6.7+/-1.6 mg/dL vs. 5.6+/-1.7 mg/dL, p < 0.05) and lower effective renal plasma flow (396+/-125 mL/min vs. 445+/-149 mL/min, p < 0.05). In conclusion, for cirrhotic patients with normal serum creatinine levels, the current study shows that the mean serum uric acid level is higher than that of healthy control subjects. It is not related to the severity of liver failure and systemic and portal hemodynamics, but is related closely to renal functions, especially the renal plasma flow.

Persistent abnormalities in plasma volume and renal hemodynamics in patients with a history of preeclampsia

OBJECTIVE: The objective was to test the hypothesis that women with a recent history of preeclampsia have abnormalities in renal hemodynamics and volume status. STUDY DESIGN: We studied a group of 26 primiparous women with history of preeclampsia and a group of 12 parous women with a history of uneventful pregnancies (control group). At least 4 months post partum we compared the following variables between these groups: effective renal plasma flow, glomerular filtration rate, plasma volume, plasma concentration of active renin, plasma concentration of angiotensin II, plasma concentration of aldosterone, and plasma concentration of atrial natriuretic peptide. RESULTS: Both plasma volume and plasma concentration of atrial natriuretic peptide were lower in the formerly preeclamptic group. Compared with the control subjects, the formerly preeclamptic group also had a lower effective renal plasma flow, a higher filtration fraction, and a higher renal vascular resistance. Intergroup differences in plasma concentration of active renin, plasma concentration of angiotensin II and plasma concentration of aldosterone were small and inconsistent. CONCLUSIONS: Women with history of preeclampsia are relatively hypovolemic and tend to have lower effective renal plasma flow and higher renal vascular resistance and filtration fraction than do control subjects. These findings support the hypothesis that otherwise healthy women with a history of preeclampsia show abnormalities in their volume status and renal hemodynamics, irrespective of their blood pressure. (Am J Obstet Gynecol 1998;179:690-6.)

Renal hemodynamics and prostaglandin E2 excretion in a nonhuman primate model of septic shock

The mechanisms responsible for renal insufficiency in septic shock (SS) have not been well characterized. We therefore investigated renal hemodynamics and the renal excretion of prostaglandin E2 (PGE2) in a nonhuman primate model of severe, low systemic vascular resistance (SVR) SS. In 18 cynomolgus monkeys, SS was induced by an infusion of 3 x 10(10) live Escherichia coli per kg; five saline-treated animals served as nonseptic controls. Systemic and renal hemodynamics, and urine PGE2 concentrations were determined over the 3 h after the induction of sepsis. The septic group demonstrated a significant (p less than .001) and sustained depression in both mean arterial pressure and SVR. Septic animals also had significantly lower effective renal plasma flow (ERPF) (p less than .01) and glomerular filtration rate (GFR) (p less than .01) compared to controls. Furthermore, the renal hemodynamic response to SS was biphasic, with significant increases in ERPF and GFR in the second hour postsepsis, followed by a pronounced decrease in the third postseptic hour. The septic group also demonstrated an increase in the renal excretion of PGE2 (p less than .001) that was temporally associated with the transient recovery in renal hemodynamics during the second postseptic hour. These sepsis-induced renal alterations may be important in the pathogenesis of renal insufficiency complicating clinical SS.

Effect of varying quantity and quality of dietary protein intake in experimental renal disease in rats.

Dietary protein restriction is known to be beneficial in the preservation of renal function when renal mass is reduced. This study investigates the effects of two different dietary proteins, casein and soya, upon renal function in normal rats and rats subjected to subtotal nephrectomy. The diets were isocaloric, with identical sodium, potassium and phosphorus contents. Normal rats ingesting a 24% soya protein diet demonstrate lower effective renal plasma flow rates and lower glomerular filtration rates than rats ingesting a 24% casein diet. Experimental animals were subjected to a unilateral nephrectomy and contralateral partial renal infarction and were fed either casein or soya, at 24 or 12% levels, for 3 months. Those animals ingesting the soya diets demonstrated improved survival (p less than 0.05), less proteinuria (p less than 0.02), less renal hypertrophy (p less than 0.005) and less renal histological damage. The nature of the dietary protein appears to influence both normal renal function and the progression of experimentally induced renal disease.

Effects of high salt intake and meclofenamate on arterial pressure and renal function in the spontaneously hypertensive rat.

1. The effects of prolonged high sodium intake (duration 3 months) and meclofenamate were studied in two groups of male spontaneously hypertensive (SH) rats. 2. Group 1 (eight rats) received 1% NaCl in water and served as controls, and group 2 received 1% NaCl in water plus meclofenamate (3.5-4.0 mg daily). 3. Group 2 rats developed higher arterial pressure, renal vascular resistance and left ventricular weight and greater renal histological changes, with lower effective renal plasma flow, renal blood flow and glomerular filtration rate, than group 1. No differences were observed between the two groups in heart rate, body weight, fluid intake, urine volume, UNaV, UKV and right ventricular weight. 4. The results suggest that the combination of high sodium intake and meclofenamate exerts a greater damaging effect on the arterial presssure and renal function of SH rats than salt alone.