Exercise training-induced hypervolemia in greyhounds: role of water intake and renal mechanisms

1985 ◽  
Vol 248 (4) ◽  
pp. R422-R425 ◽  
Author(s):  
K. H. McKeever ◽  
W. A. Schurg ◽  
V. A. Convertino
Keyword(s):  
Exercise Training ◽  
Water Intake ◽  
Significant Contribution ◽  
Free Water ◽  
Work Intensity ◽  
Water Reabsorption ◽  
Free Water Clearance ◽  
Primary Mechanism ◽  
The Mean

The purpose of this study was to determine if the chronic hypervolemia that accompanies endurance exercise training is due only to an increase in the rate of water intake or if there were contributions from renal mechanisms. Four greyhound dogs, previously sedentary for 3 yr, were utilized. During the 28-day experiment each dog was trained on a treadmill ergometer for 14 consecutive days at 65% of its pretraining maximal work intensity. After training, plasma volume increased 472 ml (27.5%, P less than 0.05). The rate of water intake increased 328 ml/day (33%, P less than 0.05), whereas urine output increased 87 ml/day (20.8%, P less than 0.05). The mean resting 24-h values for clearance of sodium increased 0.29 ml/min (90.3%, P less than 0.05), and clearance of potassium decreased 1.51 ml/min (16.1%, NS). Glomerular filtration rate, free water clearance, and osmotic clearance were not significantly altered. These data suggest that the primary mechanism for the exercise training-induced hypervolemia in dogs is a net positive water balance via increased water consumption without significant contribution from an increase in renal water reabsorption.

scholarly journals PECULIARITIES OF IONOREGULATORY RENAL FUNCTION OF RATS IN THE DYNAMICS OF EXPERIMENTAL DIABETES MELLITUS DEVELOPMENT WITH UNDERLYING PHARMACOLOGICAL BLOCADE OF RENIN-ANGIOTENSINALDOSTERONE SYSTEM

2021 ◽  
Vol 19 (4) ◽  
Author(s):  
О.А. Olenovych
Keyword(s):  
Diabetes Mellitus ◽  
Renal Function ◽  
Free Water ◽  
Distal Segment ◽  
Male Rats ◽  
Sodium Reabsorption ◽  
Free Water Clearance ◽  
Glomerular Filtrate ◽  
Pharmacological Blockade

The aim of the study – to explore the role of the renin-angiotensin-aldosteronesystem (RAAS) in the disturbance of ionoregulatory renal function in alloxan-inducedexperimental diabetes mellitus (EDM).Material and methods. The experiments were carried out on 78 white non-linearmature male rats with 11-, 26- and 46-day long alloxan-induced EDM with underlyingpharmacological blockade of RAAS by administration of kaptopril. The study ofionoregulating function of the kidneys was provided by the clearance method under thecondition of water 2-hour diuresis.Results. Pharmacological blockade of RAAS in rats with alloxan-induced EDM causedan intensification of natriuresis at all stages of the experiment: increased urinaryconcentration of sodium ions, its excretion and clearance. On the 11th day of EDM, thesodium filtration charge increased with the development of hyponatremia, proximal anddistal sodium reabsorption standardized in volume of glomerular filtrate (GF) decreased,kaliuresis was suppressed, and sodium-free water clearance elevated. In case of 26-daylong EDM, the sodium filtration charge decreased, its absolute and relative reabsorption,the distal sodium reabsorption standardized by GF increased. Kaliuresis increased. In46-day long EDM, the sodium filtration charge decreased, and hyponatremia enhanced.Absolute and relative sodium reabsorption reduced due to both – proximal and distal.Kaliuresis augmented, the clearance of sodium-free water declined.Conclusions. The increase in urinary sodium loss during the 11-day EDM is stipulatedby glomerular hyperfiltration, causing a functional weakening of the tubulotubularbalance and relative dysfunction of the distal segment of the nephron, emphasizing therenoprotective effect of RAAS on ionoregulatory function of the kidneys. The decrease inthe total reabsorption potential of the tubular segment of the nephron in the dynamics ofEDM development reflects on the proximal tubules, and preserved tubulotubular balancecertifies functional intactness of the distal tubules in 26-day long EDM. RAAS pathologicalactivation and attenuation of the renal blood flow autoregulation by tubuloglomerularfeedback may serve as an initiating factor in the development of tubular disorders in 26-day long alloxan diabetes with following progression in 46-day long EDM.

Acute effects of lithium on the renal concentrating mechanism in a primate

1975 ◽  
Vol 228 (3) ◽  
pp. 909-914 ◽  
Author(s):  
RK Webb ◽  
PB Woodhall ◽  
CC Tisher ◽  
RR Robinson
Keyword(s):  
Spontaneous Recovery ◽  
Collecting Duct ◽  
Free Water ◽  
Acute Effects ◽  
Water Reabsorption ◽  
Short Term ◽  
Free Water Clearance ◽  
Concentrating Mechanism ◽  
Renal Concentrating Mechanism ◽  
Acute Lithium

Although chronic lithium therapy has been associated with a defect in the urinary concentrating mechanism, short-term renal effects of lithium have received little attention in the intact animal. Solute-free water reabsorption (T-cH2O) and free water clearance (CH2O) were measured in primates of the genus Galago under control conditions and while animals were receiving either 0.5 mmol/kg-h or 1.0 mmol/kg-h lithium chloride (135 mM) intravenously. CH2O was unchanged by lithium infusion (P greater than 0.10), whereas T-cH2O was significantly depressed at all levels of osmolal clearance (P smaller than 0.01). Spontaneous recovery of near-normal T-cH2O was documented in two animals within 1 wk following acute lithium infusion. In addition it was observed that lithium-induced depression of T-cH2O could be partially prevented by pretreatment with intravenous amiloride. These results suggest that alterations in the renal concentrating mechanism can occur rapidly following the onset of lithium administration. They also imply that impairment of the renal concentrating mechanism by lithium is due at least in part to antagonism of the action of vasopressin on the collecting duct.

Role of distal delivery of filtrate in impaired renal dilution of the hypothyroid rat

1976 ◽  
Vol 230 (3) ◽  
pp. 699-705 ◽  
Author(s):  
UF Michael ◽  
J Kelley ◽  
H Alpert ◽  
CA Vaamonde
Keyword(s):  
Free Water ◽  
Urine Flow ◽  
Distal Nephron ◽  
Sprague Dawley ◽  
Diluting Segment ◽  
Free Water Clearance ◽  
Sprague Dawley Rats ◽  
And Control ◽  
Distal Delivery

Free water clearance (CH2O) was measured during hypotonic saline infusion in Sprague-Dawley and in Brattleboro (DI) rats with 131I-induced hypothyroidism and their age-matched controls. At peak urine flow, which was similar in hypothyroid DI (HDI) and control DI (CDI) rats, inulin clearance (CIn/kg) and CH2O/kg were 23 and 20% (P less than 0.02) lower in HDI. Fractional urine flow and fractional sodium excretion were 30 and 40% (P less than 0.001) higher in HDI. Utilization of distal delivery of filtrate for CH2O, formation was 16% less in HDI (P less than 0.01). Papillary osmolality was not higher in HDI rats. Data in Sprague-Dawley rats were similar to those of the DI rats, indicating that endogenous ADH was effectively suppressed. It is concluded: 1) delivery of filtrate out of the proximal tubule was not diminished in hypothyroid rats in spite of a decrease in CIn; 2) despite a similar delivery of filtrate to the distal diluting site, CH2O formation was less in hypothyroid rats than in controls; 3) these data suggest that a defect in the diluting segment could be unmasked at high rates of filtrate delivered to the distal nephron; 4) this defect could be either due to impaired sodium chloride reabsorption or due to increased backdiffusion of water in the distal nephron.

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.

The Role of Increased Distal Renal Tubular Filtrate Delivery in the Generation of Free Water Clearance in Cirrhotics

1990 ◽  
Vol 78 (s22) ◽  
pp. 34P-34P
Author(s):  
PA McCormick ◽  
DR Nair ◽  
Z Varghese ◽  
P Sweny ◽  
N McIntyre ◽  
...  
Keyword(s):  
Free Water ◽  
Free Water Clearance ◽  
Renal Tubular ◽  
Water Clearance

Role of ANP in natriuresis of head-out immersion in humans

1989 ◽  
Vol 257 (3) ◽  
pp. F375-F382 ◽  
Author(s):  
T. J. Rabelink ◽  
H. A. Koomans ◽  
P. Boer ◽  
C. A. Gaillard ◽  
E. J. Dorhout Mees
Keyword(s):  
Renal Plasma Flow ◽  
Water Immersion ◽  
Free Water ◽  
Urine Osmolality ◽  
Sodium Absorption ◽  
Free Water Clearance ◽  
Target Segment ◽  
Small Rise ◽  
Natriuretic Effect

Atrial natriuretic peptide (ANP) may play a role in the natriuresis after acute circulatory challenges. To assess this role in head-out water immersion (HOI), we compared in clearance studies the effect of 3 h HOI with an equally natriuretic 3-h infusion of ANP [0.01 microgram.kg-1.min-1 human ANP-(99-126)] in seven healthy individuals taking a 100 mmol sodium diet. The studies were repeated after treatment with enalapril (20 mg twice daily), which in previous studies inhibited the natriuresis after ANP. HOI caused a natriuresis equal to that of ANP infusion despite an about five times smaller rise in plasma ANP. HOI increased and ANP decreased estimated renal plasma flow (ERPF). HOI increased maximal free water clearance and decreased fractional lithium reabsorption. ANP did not affect these variables but raised minimal urine osmolality. Enalapril enhanced the fall in ERPF caused by ANP and abolished its natriuretic effect; enalapril did not impair either the natriuresis after HOI or the increase in ERPF and the fall in lithium reabsorption. These data indicate that the low dosage of ANP causes natriuresis by reducing sodium absorption in a distal nephron target segment; enalapril impairs this effect, perhaps by enhancing ANP-induced vasoconstriction, which decreases delivery to this target segment. HOI, by increasing sodium delivery to this segment, is natriuretic despite only a small rise in plasma ANP. Enalapril does not impair these effects. Although a rise in plasma ANP may be one factor in the natriuresis of HOI, the present data speak against an exclusive role. Other factors determine the magnitude of the natriuretic response.

The water intake of milking cows grazing Pangola grass (Digitaria decumbens Stent.) under wet- and dry-season conditions in Trinidad

1962 ◽  
Vol 58 (2) ◽  
pp. 257-264 ◽  
Author(s):  
P. N. Wilson ◽  
M. A. Barratt ◽  
M. H. Butterworth
Keyword(s):  
Water Intake ◽  
Free Water ◽  
Dry Season ◽  
Feed Water ◽  
Zebu Cattle ◽  
Wet Season ◽  
Drinking Habits ◽  
Digitaria Decumbens ◽  
Coefficients Of Variation ◽  
The Mean

1. The water intakes of ten Holstein × Zebu milking cows, yielding between one and two gallons of milk a day, were analysed on the basis of (a) freewater drunk, and (b) feed-water consumed with the herbage. Trials took place during a 10-day period in both the wet season, 1959 and the dry season, 1960. During both seasons the cows were rotationally grazed on Pangola grass pastures.2. The results showed a difference of only 24% in total water intake between seasons. However, the mean intake of free water increased from 18·5 lb. per cow in the wet season to 81·5 lb. per cow per day in the dry season, and the intake of feed water decreased from 94·9 to 59·2 lb. per cow per day, respectively. The between cow coefficients of variation were 9·7 and 8·7%, respectively.3. Results are presented for the drinking habits of Holstein × Zebu cattle grazing Pangola grass pastures. For 567 observed cow-days in the wet season, the cattle were found to drink water on average 0·8 times per day from troughs present in the pastures. For 332 observed cow-days in the dry season, the cattle increased their drinking habits to a mean figure of 1·4 times each day.

Plasma Dilution during Transdermal Clonidine Antihypertensive Monotherapy

1989 ◽  
Vol 12 (3) ◽  
pp. 200-203 ◽  
Author(s):  
E. T. Zawada ◽  
R. A. Jensen ◽  
L. Williams ◽  
D.W. Zeigler ◽  
M.L. Kauker
Keyword(s):  
Serum Protein ◽  
Water Intake ◽  
Serum Sodium ◽  
Free Water ◽  
Dry Mouth ◽  
Free Water Clearance ◽  
Hypertensive Patients ◽  
Protein Levels ◽  
One Year ◽  
Water Clearance

In eight hypertensive patients treated with transdermal clonidine for one year, there was plasma dilution, as shown by a reduction in serum sodium, hemoglobin, and serum protein levels. Free water clearance did not change significantly. Plasma dilution was likely sustained by increased water intake due to “dry mouth”, as frequently seen with central acting drugs such as Clonidine.

Disorders of water and sodium homeostasis

2010 ◽  
pp. 3817-3831 ◽  
Author(s):  
Michael L. Moritz ◽  
Juan Carlos Ayus
Keyword(s):  
Water Intake ◽  
Free Water ◽  
Serum Osmolality ◽  
Urinary Volume ◽  
Free Water Clearance ◽  
Water Excretion ◽  
Sodium Homeostasis ◽  
Plasma Electrolytes ◽  
Water Clearance

Water intake and the excretion of water are tightly regulated processes that are able to maintain a near-constant serum osmolality. Sodium disorders (dysnatraemias—hyponatraemia or hypernatraemia) are almost always due to an imbalance between water intake and water excretion. Understanding the aetiology of sodium disorders depends on understanding the concept of electrolyte-free water clearance—this is a conceptual amount of water that represents the volume that would need to be subtracted (if electrolyte-free water clearance is positive) or added (if negative) to the measured urinary volume to make the electrolytes contained within the urine have the same tonicity as the plasma electrolytes. It is the concentration of the electrolytes in the urine, not the osmolality of the urine, which ultimately determines the net excretion of water....

scholarly journals Charophyte variation in sensitivity to eutrophication affects their potential for the trophic and ecological status indication

2021 ◽  
pp. 30
Author(s):  
Agnieszka Kolada
Keyword(s):  
Water Quality ◽  
Significant Contribution ◽  
Ecological Status ◽  
Taxonomic Diversity ◽  
Trophic Gradient ◽  
Eutrophic Lakes ◽  
Trophic Conditions ◽  
Index Approach ◽  
The Mean

Charophytes (stoneworts) form a group of macrophytes that are considered sensitive to eutrophication. The high indicator value of charophytes toward eutrophication results in their wide use in the bioassessment systems. I explored the variability of stonewort communities' requirements for trophic conditions in lowland temperate lakes and attempted to determine the role of individual syntaxa in assessing the ecological status of lakes in Poland. The position of charophyte communities' niches along the trophic gradient was analysed using the Outlying Mean Index approach. A few stonewort communities, i.e., Nitelletum opacae, N. mucronatae, N. flexilis and Charetum filiformis appeared to be specialised concerning water quality and may be considered indicators of habitats less eutrophic than the “mean” trophic conditions in the study domain. Most stonewort communities were relatively common in European waters. Four of them, i.e., Charetum tomentosae, C. asperae, C. contrariae and Nitellopsidetum obtusae, can be classified as ‘generalists’ with low marginality and broad ecological tolerance. Most stonewort communities appeared in a broad range of ecological status classes. In the case of 15 communities, 6 to 25% of occurrences were observed in lakes representing a less than good status, and they cannot be considered indicative of good ecological conditions. However, the high taxonomic diversity and extensive phytolittoral zone were most likely to occur when the phytocoenoses of stoneworts were present. In lowland naturally eutrophic lakes inhabited by eurytopic species, the extraordinary role of charophytes in the assessment of the ecological status can be interpreted through their significant contribution to the development of the littoral.

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