scholarly journals Intermittent negative pressure ventilation may increase urine flow in normal subjects

1994 ◽  
Vol 112 (2) ◽  
pp. 551-554 ◽  
Author(s):  
Ricardo Marques Dias ◽  
Carlos Stabile ◽  
Pedro Dotto ◽  
José Roberto Jardim
Keyword(s):  
Flow Rate ◽  
Negative Pressure ◽  
Venous Blood ◽  
Urine Volume ◽  
Free Water ◽  
Normal Subjects ◽  
Urine Flow ◽  
Urine Flow Rate ◽  
Negative Pressure Ventilation ◽  
Two Phases

In order to analyze the effect of intermittent negative pressure ventilation (NPV) on renal function, we studied 20 healthy male volunteers (mean age 29±4.1 years). NPV was performed with an "Emerson Chest Respirator Pump", adjusted to a breathing frequency of 10 respirations per minute, with inspiratory time/total respiratory time ratio of 0.4 and negative pressure of 25 cmH2O. The experimental protocol was carried out in two phases of two hours each - spontaneous breathing and NPV breathing. At the end of each phase, urine volume of the whole period was collected as well as venous blood sample for biochemical determinations. During NPV there was significant increase (P<0.05) in urine flow rate (1.43±0.81 to 2.76±1.95 ml/min) as well as in natriuresis (258±201 to 389±175 mcEq/min), kaliuresis (61±45 to 98±49 mcEq/min), fractional sodium excretion (1.38±0.88 to 1.96±0.98%), osmolar clearance (3.13±1.82 to 4.32±1.24 ml/min) and pH (7.37± 0.04 to 7.41±0.07) with unchanged creatinine and free water clearances. We concluded that NPV increases urine flow rate, kaliuresis and natriuresis but the data we have do not allow us to explain the mechanisms underlying such a phenomenon.

Does a high concentration of calcium in the urine cause an important renal concentrating defect in human subjects?

2000 ◽  
Vol 98 (3) ◽  
pp. 313-319 ◽  
Author(s):  
George S. S. LAM ◽  
John R. ASPLIN ◽  
Mitchell L. HALPERIN
Keyword(s):  
Flow Rate ◽  
Human Subjects ◽  
Collecting Duct ◽  
Urine Volume ◽  
Urine Flow ◽  
Urine Flow Rate ◽  
Ionized Calcium ◽  
High Concentration ◽  
History Of ◽  
Medullary Collecting Duct

The objective of this study was to evaluate the hypothesis that a high concentration of ionized calcium in the lumen of the medullary collecting duct causes an osmole-free water diuresis. The urine flow rate and osmolality were measured in normal human subjects, as well as in patients with a history of nephrolithiasis who excreted more than 5 mmol of calcium per 24 h. There was an inverse relationship between the concentration of calcium in the urine and the 24 h urine volume both in normal subjects and in patients with a history of nephrolithiasis. When the concentration of calcium in the urine was greater than 5 mmol/l, the urine volume was less than 1 litre per day in the majority of subjects. After 16 h of water deprivation, when the concentration of calcium in the urine was as high as 17 mmol/l (ionized calcium 7.4 mmol/l), urine osmolality was 1258 mOsm/kg of water and the urine flow rate was 0.30 ml/min. We conclude that, although a calcium receptor may be present in the lumen of the medullary collecting duct in human subjects, an extremely high concentration of urinary total and ionized calcium does not cause a clinically important defect in the renal concentrating process.

Cardiovascular, renal, and endocrine responses in male quadriplegics during head-out water immersion

1990 ◽  
Vol 258 (6) ◽  
pp. R1424-R1430 ◽  
Author(s):  
F. Tajima ◽  
S. Sagawa ◽  
J. Iwamoto ◽  
K. Miki ◽  
B. J. Freund ◽  
...  
Keyword(s):  
Water Immersion ◽  
Urine Volume ◽  
Systolic Pressure ◽  
Free Water ◽  
Plasma Renin ◽  
Normal Subjects ◽  
Urine Flow ◽  
Cervical Cord ◽  
Free Water Clearance ◽  
Normal Men

The present study was undertaken to determine the relative influence of the action of the central nervous system on the mechanism of water-immersion-induced diuresis by comparing physiological responses of quadriplegic (QP) and normal subjects. After overnight fasting seven male QP subjects with complete cervical cord transections (C5-C8) and six normal men were tested before, during, and after 3 h of head-out immersion (HOI) in thermoneutral water (34.5-35.0 degrees C). The reversible increase in urine flow and the total urine volume (309 +/- 53 ml in 3 h) in QP subjects were comparable with that of the normal subjects (318 +/- 96 ml in 3 h). While osmolal excretion was increased in QP subjects, its magnitude was less when compared with that of normal subjects. Instead, the increased urine flow in QP subjects was characterized by increased glomerular filtration rate (GFR) and free water clearance, in contrast to a predominantly osmotic diuresis with no changes in GFR in the normal subjects. The HOI elevated (P less than 0.05) systolic pressure only in QP subjects, whereas the increase in cardiac output was the same in both groups. While plasma renin activity and aldosterone responses to HOI in QP subjects were comparable with those of normal individuals, plasma atrial natriuretic factor (ANF) in QP subjects was twofold higher (P less than 0.05) during HOI, and the approximately threefold increase in ANF (P less than 0.05) in QP subjects due to HOI was the same as that of normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

A Role for Sodium-Retaining Steroids in the Regulation of Proximal Tubular Sodium Reabsorption in Man

1972 ◽  
Vol 42 (4) ◽  
pp. 423-432 ◽  
Author(s):  
John R. Gill ◽  
Catherine S. Delea ◽  
F. C. Bartter
Keyword(s):  
Flow Rate ◽  
Sodium Excretion ◽  
Free Water ◽  
Urine Flow ◽  
Urine Flow Rate ◽  
Diluting Segment ◽  
Free Water Clearance ◽  
Urinary Osmolality ◽  
Glomerular Filtrate ◽  
Water Clearance

1. The response to an infusion of 4% (w/v) fructose in water was determined in fifteen women on a daily sodium intake of 100 mEq/day. The results were compared with those obtained during a similar infusion on another day after treatment with deoxycorticosterone (20 mg/day; seven subjects), or spironolactone (200 mg/day; eight subjects), for 1 day before the day of study. 2. Treatment with deoxycorticosterone significantly (P < 0·01) decreased sodium excretion (from a mean value of 391 to 192 μEq/min) and urine flow rate (from 14·3 to 12·4 ml min−1 100 ml−1 of glomerular filtrate) without a change in urinary osmolality or the clearance of inulin. The steroid also increased the fractional reabsorption of sodium at the diluting segment of the nephron, but this increase in reabsorption was not sufficient to compensate for the decrease in delivery of sodium to the site, so that absolute free-water clearance decreased. 3. Treatment with spironolactone significantly (P < 0·01) increased sodium excretion (from 349 to 437 μEq/min) and urine flow rate (from 12·5 to 14·4 ml min−1 100 ml−1 of glomerular filtrate) with essentially no change in urinary osmolality or in inulin clearance. Spironolactone also decreased the fractional reabsorption of sodium at the diluting segment of the nephron, but the degree of inhibition of reabsorption was not sufficient to prevent an increase in free-water clearance as a result of increased delivery of sodium to the site. 4. The findings support the concept that changes in circulating aldosterone can alter the renal excretion of sodium in man by affecting its reabsorption in the proximal tubule as well as in the distal tubule.

Atrial natriuretic peptide response to rapid atrial pacing in cardiac-denervated dogs

1989 ◽  
Vol 257 (1) ◽  
pp. R162-R167 ◽  
Author(s):  
T. D. Williams ◽  
K. P. Walsh ◽  
R. Canepa-Anson ◽  
M. I. Noble ◽  
A. J. Drake-Holland ◽  
...  
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Flow Rate ◽  
Free Water ◽  
Urine Flow ◽  
Urine Flow Rate ◽  
Right Atrial ◽  
Atrial Pacing ◽  
Cardiac Denervation ◽  
Atrial Natriuretic

The effects of rapid atrial pacing on central hemodynamics, plasma hormones, and renal function were investigated in eight control and nine cardiac-denervated dogs under chloralose anesthesia. Pacing at approximately 250 ppm for 60 min caused similar increases in pulmonary wedge and right atrial pressures, systemic vascular resistance, and plasma atrial natriuretic peptide (ANP) in both groups. In control dogs, pacing produced a fall in both plasma vasopressin (AVP) and plasma renin activity (PRA) and a rise in urine flow rate associated with an increase in free water but not sodium clearance. In contrast, in cardiac-denervated dogs, both plasma AVP and PRA increased during pacing; urine flow rate did not change, and marked sodium retention occurred. This study supports the concept that the increase in urine flow during rapid atrial pacing is mediated by inhibition of renin and AVP secretion through intact cardiac nerves. The secretion of ANP is unaffected by cardiac denervation. The natriuretic and vasodilator actions of high plasma ANP concentrations during rapid atrial pacing can be inhibited either by neurally mediated cardiorenal effects in normal animals or by stimulation of the renin-angiotensin system after cardiac denervation.

Decreased vasopressin-mediated renal water reabsorption in rats with compensated liver cirrhosis

1998 ◽  
Vol 275 (2) ◽  
pp. F216-F225 ◽  
Author(s):  
Thomas E. N. Jonassen ◽  
Søren Nielsen ◽  
Sten Christensen ◽  
Jørgen Søberg Petersen
Keyword(s):  
Flow Rate ◽  
Water Channel ◽  
Free Water ◽  
Test Dose ◽  
Urine Flow ◽  
Urine Flow Rate ◽  
Thick Ascending Limb ◽  
Receptor Blockade ◽  
Water Reabsorption ◽  
Outer Medulla

Experiments were performed to investigate vasopressin type 2 receptor (V2)-mediated renal water reabsorption and the renal expression of the vasopressin-regulated water channel aquaporin-2 (AQP-2) in cirrhotic rats with sodium retention but without ascites. In addition, the expression of the furosemide-sensitive type 1 Na-K-2Cl cotransporter (BSC-1) and the natriuretic response to an intravenous test dose furosemide (7.5 mg/kg) during acute V2-receptor blockade was measured. Acute V2-receptor blockade with the selective nonpeptide antagonist OPC-31260 (800 μg ⋅ kg−1 ⋅ h−1) was performed during conditions in which volume depletion was prevented by computer-driven, servo-controlled intravenous volume replacement with 150 mM glucose. OPC-31260 produced a significantly smaller increase in urine flow rate (−26%) and free water clearance (−18%) in cirrhotic rats than in control rats. The natriuretic response to an intravenous test dose furosemide (7.5 mg/kg) was significantly increased in cirrhotic rats (+52%), but pretreatment with OPC-31260 did not affect the natriuretic response to furosemide in neither cirrhotic nor in control rats. Semiquantitative immunoblotting showed a significant downregulation of AQP-2 in the renal cortex (−72%) and in the outer medulla (−44%). The relative expression of BSC-1 in the outer medulla was unchanged in cirrhotic rats. The corticopapillary gradient of Na was significantly increased in cirrhotic rats. Since daily urine flow rate was similar in cirrhotic and sham-operated rats, we suggest that non-vasopressin-mediated water reabsorption is increased in cirrhotic rats probably as a result of an increased corticomedullary gradient due to exaggerated NaCl reabsorption in the thick ascending limb of Henle’s loop.

Inter-relationship between urinary kallikrein-kinins and arginine vasopressin in man

1989 ◽  
Vol 76 (1) ◽  
pp. 13-18 ◽  
Author(s):  
K. Yamada ◽  
K. Hasunuma ◽  
T. Shiina ◽  
K. Ito ◽  
Y. Tamura ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
Arginine Vasopressin ◽  
Control Period ◽  
Urine Volume ◽  
Free Water ◽  
Normal Subjects ◽  
Urine Flow ◽  
Urinary Kallikrein ◽  
Plasma Aldosterone Concentration ◽  
Water Loading

1. Physiological saline solution was infused in nine normal subjects and six patients with central diabetes insipidus (DI). At 120 min after the start of infusion, arginine vasopressin (AVP) was injected intramuscularly. Urine was collected in 30 min fractions before and after AVP administration. 2. The urinary excretions of kallikrein-like activity (KAL-A) (S-2266 hydrolysis activity) and immunoreactive kinins (i-kinins) were significantly lower in patients with DI than in normal subjects before AVP administration, while there were no differences in plasma renin activity, plasma aldosterone concentration, creatinine clearance and blood pressure between the two groups, except for a marked water diuresis in patients with DI. The urinary excretion of KAL-A and i-kinins correlated positively with the urinary excretion of AVP. 3. AVP administration increased both plasma AVP and urinary excretion of AVP to similar levels in both groups. As a result, urine volume decreased to a greater degree in patients with DI than in normal subjects. In contrast, the urinary excretions of KAL-A and i-kinins were increased by AVP administration, with a greater response in normal subjects than in the patients with DI. 4. After overnight fasting, acute water loading was carried out orally for 15 min in six normal subjects. At 30 min plasma AVP was suppressed by water loading to almost the basal level found in patients with DI. Urinary excretions of KAL-A and i-kinins in the first 30 min fraction after loading were also suppressed to the basal level in patients with DI. Later, the urinary excretion of KAL-A increased together with the increase in urine flow. Urine volume and free water clearance markedly increased except in the first 30 min fraction, compared with the control period. 5. Thus it is suggested that AVP is one of the factors regulating the renal kallikrein-kinin system in man, although it seems likely that urine flow is still a major factor in urinary kallikrein-kinin excretion.

Factors affecting the urinary excretion of urea nitrogen in cattle. I. Sodium chloride and water loads

1970 ◽  
Vol 21 (1) ◽  
pp. 131 ◽  
Author(s):  
RF Thornton
Keyword(s):  
Sodium Chloride ◽  
Flow Rate ◽  
Free Water ◽  
Urine Flow ◽  
Urea Concentration ◽  
Urine Flow Rate ◽  
Urea Nitrogen ◽  
Plasma Urea ◽  
Urea Excretion ◽  
Plasma Urea Concentration

Urea metabolism in cattle was studied under conditions of different nitrogen, sodium chloride, and water intakes. Urea supplementation increased the concentrations of ammonia and trichloroacetic acid-insoluble nitrogen in ventral rumen fluid, raised the plasma urea concentration, and increased the excretion of faecal nitrogen and urinary urea and non-urea nitrogen. Sodium chloride loading increased the free water intake and urine flow rate, and the added sodium was quantitatively recovered in the urine. Plasma urea concentration was linearly related to urinary urea excretion but the slope of this relationship was influenced by the urine flow rate. Urea clearance and the fraction of filtered urea excreted were both related to the urine flow rate and to the urine-concentrating ability of the kidney, but not to the urinary urea output. During low nitrogen intakes, urinary urea excretion was influenced more by urine flow than by solute load.

scholarly journals Minimum urine flow rate during water deprivation: importance of the nonurea versus total osmolality in the inner medulla.

1997 ◽  
Vol 8 (6) ◽  
pp. 880-886
Author(s):  
S D Soroka ◽  
S Chayaraks ◽  
S Cheema-Dhadli ◽  
J A Myers ◽  
S Rubin ◽  
...  
Keyword(s):  
Flow Rate ◽  
Water Conservation ◽  
Water Deprivation ◽  
Interstitial Fluid ◽  
Collecting Duct ◽  
Normal Subjects ◽  
Urine Flow ◽  
Urine Flow Rate ◽  
Urea Excretion ◽  
Medullary Collecting Duct

Antidiuretic hormone leads to an increase in the permeability for water and urea in the inner medullary collecting duct. Hence, urea may not be an "effective" osmole in the inner medulla during maximal renal water conservation. Accordingly, the purpose of this study was to evaluate whether differences in the rate of urea excretion would influence maximum renal water conservation in humans. In water-deprived rats, the concentration of urea and total osmolality were somewhat higher in the urine exiting the inner medullary collecting duct than in interstitial fluid obtained from the entire papillary tip. Nevertheless, the "nonurea" (total osmolality minus urea in millimolar terms) osmolality was virtually identical in both locations. Chronically fasted human subjects that were water-deprived for 16 h had a lower rate of urea excretion (71 +/- 7 versus 225 +/- 14 mumol/min) and a somewhat lower urine osmolality (745 +/- 53 versus 918 +/- 20 mosmol/kg H2O). Nevertheless, they had identical urine flow rates (0.5 +/- 0.01 and 0.5 +/- 0.02 ml/min, respectively), and their nonurea osmolality also was similar (587 +/- 25 and 475 +/- 14 mosmol/kg H2O, respectively) to the water-deprived normal subjects. The composition of their urine differed in that the principal nonurea osmoles became NH4+ and beta-hydroxybutyrate rather than Na and C1. During water deprivation in normal subjects, the ingestion of urea caused a twofold rise in urine flow rate, a fall in the nonurea osmolality, and a rise in the rate of excretion of nonurea osmoles. The nonurea osmolality of the urine, and presumably the medullary interstitial fluid as well, was inversely related to the urea excretion rate. In chronic fasting, the nature, but not the quantity, of nonurea osmoles changed. The similar minimum urine volume was predictable from an analysis based on nonurea osmole considerations.

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.

Sign in / Sign up

Export Citation Format

Share Document