Flow rate of urine as a determinant of renal countercurrent multiplier system

1960 ◽  
Vol 199 (5) ◽  
pp. 919-922 ◽  
Author(s):  
Peter H. Abbrecht ◽  
Richard L. Malvin
Keyword(s):  
Flow Rate ◽  
Renal Plasma Flow ◽  
Smooth Curve ◽  
Sodium Concentration ◽  
Urine Flow ◽  
Mathematical Treatment ◽  
Urine Osmolarity ◽  
Ureteral Catheter ◽  
Multiplier System ◽  
Sodium Gradient

The mathematical treatment of the renal countercurrent multiplier system predicts that the rates of flow of urine and blood through the medullary loops are determinants of the maximal osmolarity which may be established in the medullary interstitium. It was found that acute increases in the urine flow rate resulted in a concomitant increase in the sodium concentration of the urine. The relation between urine flow rates and urine osmolarity was studied more closely. During osmotic diuresis the GFR of one kidney was reduced independently of the renal plasma flow by partially occluding one ureteral catheter. This resulted in an increase in urine osmolarity from that kidney. The increase in urine osmolarity correlated with an increase in the medullary sodium gradient. A smooth curve was obtained relating urine osmolarity to percent reduction of GFR. Urine osmolarity increased as the GFR was reduced, reaching a maximum at 70% reduction in GFR. Greater reductions of GFR resulted in decreasing osmolarities.

Effect of urine flow rate on uric acid excretion in man

1972 ◽  
Vol 15 (4) ◽  
pp. 338-346 ◽  
Author(s):  
Herbert S. Diamond ◽  
Robert Lazarus ◽  
David Kaplan ◽  
David Halberstam
Keyword(s):  
Uric Acid ◽  
Flow Rate ◽  
Urine Flow ◽  
Urine Flow Rate ◽  
Acid Excretion ◽  
Uric Acid Excretion

Homeostatic potassium excretion in fed and fasted sheep

1988 ◽  
Vol 254 (2) ◽  
pp. R357-R380 ◽  
Author(s):  
L. Rabinowitz ◽  
D. M. Green ◽  
R. L. Sarason ◽  
H. Yamauchi
Keyword(s):  
Flow Rate ◽  
Urine Flow ◽  
Plasma Aldosterone ◽  
Urine Flow Rate ◽  
Potassium Excretion ◽  
Adult Sheep ◽  
Blood Ph ◽  
Low Levels ◽  
K Concentration ◽  
Filtered Load

In unanesthetized adult sheep, following intake of a daily meal, there was a peak in K excretion. The maximum and minimum rates of K excretion following meals were directly related to meal K content. On days without meals, no peak in K excretion occurred. Changes in K excretion on fed and fast days occurred without changes in the low levels of plasma aldosterone and were poorly correlated with urine or blood pH, urine flow rate, Na excretion, or the filtered load of K, but they correlated well with fractional K excretion. Plasma K did not change on fast days. Plasma K increased on some, but not all, fed days. Increases in plasma K that occurred on fed days were insufficient to account for the concurrent kaliuresis. Infusion of aldosterone or isotonic NaCl failed to alter K excretion in fed or fasted sheep. Infusion of isotonic NaCl + aldosterone hypertonic Na2SO4 + aldosterone increased K excretion in fasted but not fed sheep. Infusion of K in the rumen of fed and fasted sheep elevated rumen K concentration and led to increases in K excretion that could not be explained by increases in plasma K. The mechanisms responsible for the homeostatic changes in K excretion on fed and fast days were not ascertained but may importantly depend on sensors of enteric K content.

Renal responses to graded hemorrhage in conscious pig

1990 ◽  
Vol 259 (1) ◽  
pp. R119-R125 ◽  
Author(s):  
J. L. Sondeen ◽  
G. A. Gonzaludo ◽  
J. A. Loveday ◽  
G. E. Deshon ◽  
C. B. Clifford ◽  
...  
Keyword(s):  
Blood Flow ◽  
Glomerular Filtration Rate ◽  
Arterial Pressure ◽  
Filtration Rate ◽  
Urine Flow ◽  
Electrolyte Excretion ◽  
Flow Probe ◽  
Ureteral Catheter ◽  
Time Points ◽  
Renal Responses

We developed a conscious pig model with a chronically instrumented kidney to measure renal blood flow (RBF), glomerular filtration rate (GFR), and excretory functions during hemorrhage. Seven to 10 days before experimentation, pigs were splenectomized, arterial and venous catheters were implanted, an ultrasonic flow probe was placed on the renal artery, and a pyelostomy was performed for nonocclusively placing a ureteral catheter. Measurements were taken before hemorrhage, and at hemorrhage volumes of 7, 14, 21, and 28 ml/kg (equivalent to 10.5, 21, 31, and 42% of the estimated blood volume), or at corresponding time points for controls. RBF was decreased by 30% when 21% of the blood (14 mg/kg) was removed, before arterial pressure, GFR, or urine flow or excretion was changed. At volumes of hemorrhage greater than 14 ml/kg, there were progressive decreases in RBF, GFR, urine flow rate, osmotic and electrolyte excretion, and arterial pressure. Thus pigs, like humans, respond to hypovolemia with an early redistribution of blood flow away from the kidney.

The role of transmembrane sodium gradient in rabbit ileal smooth muscle: Utilization of harmaline

1985 ◽  
Vol 5 (8) ◽  
pp. 667-671 ◽  
Author(s):  
M. S. Suleiman
Keyword(s):  
Smooth Muscle ◽  
Contractile Response ◽  
Sodium Concentration ◽  
Exchange Mechanism ◽  
Dependent Manner ◽  
Sodium Gradient ◽  
Extracellular Sodium ◽  
Dose Dependent

Decreasing extracellular sodium concentration was found to produce a contractile response of rabbit ileal smooth muscle. As the concentration decreases, the amplitude of contraction increases, thus producing a dose-dependent curve. Harmaline, a competitor for sodium, was found to inhibit the sodium gradient-dependent contractions in a dose-dependent manner. The results are interpreted as harmaline inhibiting a Na–Ca exchange mechanism present in ileal smooth muscle.

Urine Quantification Following Furosemide for Severe Acute Kidney Injury Prediction in Critically Ill Children

2021 ◽  
Author(s):  
Katja M. Gist ◽  
Jamie Penk ◽  
Eric L. Wald ◽  
Laura Kitzmiller ◽  
Tennille N. Webb ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Cardiac Surgery ◽  
Critically Ill ◽  
Flow Rate ◽  
Kidney Injury ◽  
Urine Flow ◽  
Urine Flow Rate ◽  
Critically Ill Children ◽  
Prospective Assessment ◽  
Critically Ill Adults

AbstractA standardized, quantified assessment of furosemide responsiveness predicts acute kidney injury (AKI) in children after cardiac surgery and AKI progression in critically ill adults. The purpose of this study was to determine if response to furosemide is predictive of severe AKI in critically ill children outside of cardiac surgery. We performed a multicenter retrospective study of critically ill children. Quantification of furosemide response was based on urine flow rate (normalized for weight) measurement 0 to 6 hours after the dose. The primary outcome was presence of creatinine defined severe AKI (Kidney Disease Improving Global Outcomes stage 2 or greater) within 7 days of furosemide administration. Secondary outcomes included mortality, duration of mechanical ventilation and length of stay. A total of 110 patients were analyzed. Severe AKI occurred in 20% (n = 22). Both 2- and 6-hour urine flow rate were significantly lower in those with severe AKI compared with no AKI (p = 0.002 and p < 0.001). Cutoffs for 2- and 6-hour urine flow rate for prediction of severe AKI were <4 and <3 mL/kg/hour, respectively. The adjusted odds of developing severe AKI for 2-hour urine flow rate of <4 mL/kg/hour was 4.3 (95% confidence interval [CI]: 1.33–14.15; p = 0.02). The adjusted odds of developing severe AKI for 6-hour urine flow rate of <3 mL/kg/hour was 6.19 (95% CI: 1.85–20.70; p = 0.003). Urine flow rate in response to furosemide is predictive of severe AKI in critically ill children. A prospective assessment of urine flow rate in response to furosemide for predicting subsequent severe AKI is warranted.

Renal Function in Unanaesthetized River Lampreys (Lampetra FluviatilisL.): Effects of Anaesthesia, Temperature and Environmental Salinity

1983 ◽  
Vol 105 (1) ◽  
pp. 351-362 ◽  
Author(s):  
A. J. MCVICAR ◽  
J. C. RANKIN
Keyword(s):  
Renal Function ◽  
Flow Rate ◽  
Ventilation Rate ◽  
Urine Flow ◽  
The Body ◽  
Urine Flow Rate ◽  
Flow Rates ◽  
Gill Ventilation ◽  
Daily Excretion ◽  
The Mean

1. Improved estimates of urine flow rates of lampreys in various salinities were obtained by the collection of urine for periods of up to 48 h from minimally-stressed, unanaesthetized fish, following catheterization of the urinogenital papilla. 2. The mean urine flow rate of freshwater lampreys was 200.7 ±14.3 ml kg−1 day−1. 3. Urine flow in freshwater lampreys was correlated with spontaneous changes in gill ventilation rate. MS222 anaesthesia reduced both ventilation and urine flow rates, but pronounced effects were only observed at concentrations greater than those needed to induce light anaesthesia (50–55 mg 1−1). Urine flow rate in unanaesthetized fish was extremely sensitive to rapid (6°Ch−1) changes in temperature and Q10 (6–16°C) was approximately 5. 4. Urine flow rate decreased rapidly as the osmotic difference between the body fluids and environment approached zero, and the rate of flow in 30% seawater lampreys was only 7.6% that of freshwater fish. 5. There was no evidence for an effect of environmental calcium concentration on branchial osmotic permeability. 6. Extensive tubular reabsorption of ions occurred in freshwater lampreys. The total daily excretion rate of sodium ions generally decreased in salinities hyperosmotic to the plasma, indicating enhanced reabsorption, but secretion of magnesium and sulphate ions was greatly increased. Urine osmolarity was significantly increased in lampreys in hyperosmotic salinities. 7. Present data compare favourably with data obtained previously from anaesthetized animals, indicating that renal function in lampreys is not significantly impaired by light MS222 anaesthesia.

Mechanism underlying diuretic effect of l-NAME at a subpressor dose

2001 ◽  
Vol 281 (3) ◽  
pp. F414-F419 ◽  
Author(s):  
Mingyu Liang ◽  
Theresa J. Berndt ◽  
Franklyn G. Knox
Keyword(s):  
Proximal Tubule ◽  
Flow Rate ◽  
Nitrate Concentration ◽  
Distal Tubule ◽  
No Synthase ◽  
Urine Flow ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Renal Tubular ◽  
Nitrite Nitrate

The diuretic effects of nitric oxide (NO) synthase inhibitors administered at subpressor dose in rats are controversial, and the tubular segments involved are not known. In the present study, we examined the effect of N ω-nitro-l-arginine methyl ester (l-NAME) at a subpressor dose on renal interstitial NO and cGMP activity and on renal tubular segmental reabsorption of fluid in the rat. Intravenous infusion of l-NAME at 1 μg · kg−1 · min−1 in Sprague-Dawley rats ( N = 8), which did not alter mean arterial pressure or glomerular filtration rate, significantly increased urine flow rate (Uv; from 78.2 ± 12.7 to 117.1 ± 14.9 μl/min, P < 0.05). Paradoxically, this effect of l-NAME was concomitant with significant increases in nitrite/nitrate (from 10.79 ± 1.20 to 16.50 ± 2.60 μM, P < 0.05) and cGMP (from 0.65 ± 0.09 to 0.98 ± 0.18 nM, P < 0.05) concentrations in renal cortical microdialysate as well as the nitrite/nitrate concentration in the medullary microdialysate. Micropuncture studies in the superficial nephron revealed that l-NAME significantly increased the flow rate (from 8.3 ± 0.9 to 12.2 ± 1.2 nl/min, P < 0.05) and fractional delivery of fluid to the distal tubule, but not those in the late proximal tubule. In conclusion, l-NAME, at the subpressor dose used in this study, increased renal nitrate/nitrite and cGMP and inhibited fluid reabsorption in tubular segments between the late proximal tubule and the distal tubule of superficial nephrons.

scholarly journals Contrasting pharmacological ETB receptor blockade with genetic ETB deficiency in renal responses to big ET-1

2001 ◽  
Vol 6 (1) ◽  
pp. 39-43 ◽  
Author(s):  
DAVID M. POLLOCK
Keyword(s):  
Renal Plasma Flow ◽  
Urine Flow ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Clearance Studies ◽  
Etb Receptor ◽  
Pharmacological Blockade ◽  
Series Of Experiments ◽  
Renal Responses

Renal clearance studies were conducted to determine the role of ETB receptors in the renal response to big endothelin-1 (big ET-1). Two series of experiments were conducted on Inactin-anesthetized rats to contrast acute pharmacological blockade of ETB receptors vs. genetic ETB receptor deficiency. In the first series, Sprague-Dawley rats were given either ETB-selective antagonist, A-192621, or vehicle (0.9% NaCl) prior to infusion of big ET-1 (10 pmol·kg−1·min−1) for 60 min. A-192621 significantly increased baseline mean arterial pressure (MAP; 102 ± 4 vs. 141 ± 6 mmHg, P < 0.05) and urine flow rate (0.5 ± 0.1 vs. 1.3 ± 0.2 μl/min, P < 0.05) without any effect on glomerular filtration rate (GFR) or effective renal plasma flow (ERPF). Big ET-1 significantly increased MAP in both groups but to a higher level in rats given antagonist (120 ± 6 vs. 169 ± 6 mmHg, P < 0.05). Big ET-1 increased urine flow in control rats but decreased in rats given antagonist. GFR and ERPF were decreased in rats given big ET-1, an effect that was exaggerated by ETB blockade. Another series of experiments examined the response to big ET-1 in rats lacking functional renal ETB receptors, known as spotting lethal ( sl) rats. Surprisingly, rats heterozygous ( sl/+) for ETB receptor deficiency had a significantly higher baseline MAP compared with homozygous ( sl/ sl) rats (134 ± 6 vs. 112 ± 7 mmHg, P < 0.05), although other variables were similar. Big ET-1 produced no significant change in MAP in either group. Urine flow, GFR, and ERPF were significantly decreased in both groups, although these changes were much larger in sl/ sl rats. These experiments indicate that the ETB receptor plays an important role in limiting the renal hemodynamic response to big ET-1. Furthermore, the diuretic actions of big ET-1 require a functional ETB receptor.

Exogenous cGMP prevents decrease in diuresis and natriuresis induced by inhibition of NO synthesis

1993 ◽  
Vol 264 (2) ◽  
pp. F344-F347 ◽  
Author(s):  
V. Lahera ◽  
J. Navarro ◽  
M. L. Biondi ◽  
L. M. Ruilope ◽  
J. C. Romero
Keyword(s):  
Nitric Oxide ◽  
Intravenous Infusion ◽  
Filtration Rate ◽  
Excretion Rate ◽  
Renal Plasma Flow ◽  
Specific Inhibitor ◽  
Urine Flow ◽  
Dibutyryl Camp ◽  
Excretory Function ◽  
Preventive Effects

We previously demonstrated that the intravenous infusion of the specific inhibitor of nitric oxide (NO) synthesis, NG-nitro-L-arginine methyl ester (L-NAME), over a period of 60 min elevates mean arterial pressure (MAP) and reduces renal hemodynamics and excretory function. The objective of the present study was to determine the ability of a guanosine 3',5'-cyclic monophosphate (cGMP) analogue, 8-bromo-cGMP (8-BrcGMP), in preventing the increase in MAP and the reductions in renal plasma flow (RPF), glomerular filtration rate (GFR), urine flow (UV), and sodium excretion rate (UNaV) induced by intravenous infusion of L-NAME in rats. As expected, the infusion of L-NAME (50 micrograms.kg-1.min-1) increased (P < 0.05) MAP and reduced (P < 0.05) RPF, GFR, UV, and UNaV. The administration of 8-BrcGMP (100 micrograms.kg-1.min-1) and L-NAME resulted in no change in MAP, RPF, and GFR. However, decreased (P < 0.05) UV and UNaV were still observed. When 8-BrcGMP (200 micrograms.kg-1.min-1) and L-NAME were infused together, no significant changes in MAP or in renal function were observed. To prove the specificity of the 8-BrcGMP preventive effects, dibutyryl cAMP (200 micrograms.kg-1.min-1) and L-NAME (50 micrograms.kg-1.min-1) were infused together. Under these conditions, MAP, RPF, GFR, UV, and UNaV were modified in a manner similar to that observed during the infusion of L-NAME.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal function in the chronically cannulated fetal llama: comparison with studies in the ovine fetus

1995 ◽  
Vol 7 (5) ◽  
pp. 1311 ◽  
Author(s):  
EM Wintour ◽  
R Riquelme ◽  
C Gaete ◽  
C Rabasa ◽  
E Sanhueza ◽  
...  
Keyword(s):  
Amniotic Fluid ◽  
Flow Rate ◽  
Urine Flow ◽  
Urine Flow Rate ◽  
Fetal Kidney ◽  
Fetal Plasma ◽  
Post Surgery ◽  
Fetal Urine ◽  
Ovine Fetus ◽  
Ovine Fetal

Samples of maternal and fetal plasma, fetal urine, and amniotic fluid were collected from 8 chronically cannulated pregnant llamas, in the last third of gestation. The samples were obtained for up to 18 days post-surgery. Osmolality, sodium (Na), potassium (K), chloride (Cl), and urea were measured on 40 samples collected on days 1, 2, 3, 4-5, 6-7, 8-9, and 10-19. The osmolalities of maternal and fetal plasma, fetal urine and amniotic fluid, averaged over these 7 time periods, were, respectively, 312 +/- 2, 311 +/- 1, 484 +/- 14, and 317 +/- 1 mosmol kg-1. Values are given as mean +/- s.e. The major differences from fetal fluid values in the ovine fetus (from previously published values) were the higher osmolality and urea concentration of llama fetal urine. Urine flow rate measured in 6 fetuses, 4.5-6.5 kg body weight, was 5.8 +/- 0.4 mliter h-1; urea clearance rate was 55.5 +/- 11.8 mliter h-1. Glomerular filtration rate (GFR), measured with 51Cr-EDTA in 5 fetuses on 1-4 occasions, was 111.4 +/- 23.3 mliter h-1. Fractional reabsorptions (FR) of Na, K and Cl were 97.9 +/- 1, 75.9 +/- 13.5 and 97.7 +/- 0.4% respectively. The GFR (25 mliter kg-1 h-1) and urine flow rate (1 mL kg-1 h-1) were less than half and about one-tenth the respective values in ovine fetuses. As Na reabsorption is the major oxygen-consuming activity of the kidney, the llama fetal kidney requires only half the oxygen needed by the ovine fetal kidney to reabsorb the filtered sodium load. The reason for the formation of hypertonic, rather than hypotonic, urine in the fetal llama may be due to both greater morphological maturity of the kidney and the excretion of as yet unidentified osmotically active organic substances.

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