Free Water Clearance in Patients with Essential Hypertension

1973 ◽  
Vol 45 (4) ◽  
pp. 469-477
Author(s):  
E. J. Dorhout Mees ◽  
H. de Graaf
Keyword(s):  
Salt Intake ◽  
Free Water ◽  
Normal Subjects ◽  
Mean Value ◽  
Exponential Relationship ◽  
Free Water Clearance ◽  
Uncomplicated Hypertension ◽  
The Mean ◽  
Different Levels ◽  
Water Clearance

1. Free water clearance (CH2O) was measured in sixteen normal subjects and twenty-five patients with uncomplicated hypertension at different levels of salt intake. 2. In normal subjects CH2O and Na+ excretion were related thus: log Na+ excretion = 0·1685 + 0·1508 × CH2O. At a given value for Na+ excretion the standard deviation for CH2O was ±1·5 ml min−1. 3. The mean value for the ratio CH2O/creatinine clearance was higher in the hypertensive patients than in controls at all levels of Na+ excretion. 4. Most previous studies reporting decreased values for CH2O in hypertension can be explained by the exponential relationship between CH2O and Na+ excretion.

Osmotic thresholds for AVP release with the use of plasma and urine AVP and free water clearance

1989 ◽  
Vol 256 (4) ◽  
pp. R892-R897 ◽  
Author(s):  
A. M. Moses
Keyword(s):  
Plasma Osmolality ◽  
Free Water ◽  
Normal Subjects ◽  
Free Water Clearance ◽  
Linear Relationships ◽  
Osmotic Stimulation ◽  
Glomerular Filtrate ◽  
The Mean ◽  
The Relationship ◽  
Water Clearance

Eleven hydrated normal subjects were infused with hypertonic saline so that plasma osmolalities (POsmol) ranged from 280 to 306 mosmol/kg. Linear relationships were calculated between POsmol and plasma and urine arginine vasopressin (AVP) in the 11 individual subjects. There was an excellent linear correlation between POsmol and plasma and urine AVP, with the latter as concentration or rate of excretion. The highest correlation coefficient occurred when urine AVP was expressed as microunits of AVP per 100 milliliters of glomerular filtrate. The smallest coefficient of variation of the slopes occurred when urine AVP was expressed as microunits of AVP per minute. The osmotic thresholds obtained by abscissal intercepts from relating POsmol to urine AVP per minute or per 100 milliliters of glomerular filtrate were 285.9 and 285.5 mosmol/kg, respectively. These values did not differ from the mean osmotic threshold obtained by traditional free water clearance changes (285.8 mosmol/kg). Analysis of the relationship between plasma osmolality and plasma AVP resulted in the greatest variation in slope and osmotic threshold, with the latter being significantly lower than that obtained by free water clearance changes. The data also demonstrated a much more rapid rise of urine than of plasma AVP under the stated conditions of osmotic stimulation.

Regulation and function of arginine vasopressin in pregnant sheep

1986 ◽  
Vol 250 (5) ◽  
pp. F777-F780 ◽  
Author(s):  
R. J. Bell ◽  
B. M. Laurence ◽  
P. J. Meehan ◽  
M. Congiu ◽  
B. A. Scoggins ◽  
...  
Keyword(s):  
Arginine Vasopressin ◽  
Infusion Rate ◽  
Plasma Osmolality ◽  
Free Water ◽  
Urinary Flow ◽  
Free Water Clearance ◽  
Pregnant Sheep ◽  
The Mean ◽  
And Function ◽  
Water Clearance

The aim of this study was to investigate the regulation and function of arginine vasopressin (AVP) in pregnant sheep. The mean plasma osmolality of nonpregnant ewes (298 +/- 1.0 mosmol/kg, n = 8) was not significantly different from that of late pregnant ewes (295 +/- 1.1 mosmol/kg, n = 21). The mean resting plasma [AVP] of nonpregnant ewes (4.1 +/- 0.6 pg/ml,n = 8) was not significantly different from that of pregnant ewes (3.3 +/- 0.3 pg/ml,n = 21). In a series of dehydration experiments it was established that the slope of the function relating log [AVP] to plasma osmolality for pregnant ewes (n = 13) was not significantly different from the slope of the function relating log [AVP] to plasma osmolality for nonpregnant ewes (n = 4). When AVP was infused into water-loaded ewes, a significant decrease in urinary flow rate and free water clearance occurred at an infusion rate of 0.003 microgram/h in both the pregnant (n = 4) and nonpregnant (n = 4) animals. Both groups achieved negative free water clearance at an infusion rate of 0.01 microgram/h. These findings suggest that pregnancy does not alter the relationship between plasma osmolality and plasma [AVP] or the renal responsiveness to AVP in sheep.

THE EFFECT OF FUROSEMIDE, A NEW DIURETIC AGENT, ON RENAL CONCENTRATING AND DILUTING MECHANISMS

1966 ◽  
Vol 44 (1) ◽  
pp. 129-137 ◽  
Author(s):  
Peter A. F. Morrin
Keyword(s):  
Free Water ◽  
Normal Subjects ◽  
Water Diuresis ◽  
Free Water Clearance ◽  
Henle's Loop ◽  
Diuretic Agent ◽  
Site Of Action ◽  
Glomerular Filtrate ◽  
Water Clearance

The effect of a new diuretic, Furosemide, has been studied in normal subjects undergoing both osmotic and water diuresis. A marked increase in the excretion of sodium and water was observed, the latter amounting to 30% of the glomerular filtrate. In the hydropenic subjects the drug virtually abolished negative free water clearance, which indicates that the site of action is in the ascending limb of Henle's loop. In the water-loaded subjects, free water clearance was decreased but not abolished, which suggests that urinary dilution distal to the ascending limb of Henle's loop is not significantly impaired by the diuretic.

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