Salt saving in the pregnant rat

1961 ◽  
Vol 201 (5) ◽  
pp. 765-768 ◽  
Author(s):  
I. J. Lichton
Keyword(s):  
Saline Solution ◽  
Isotonic Saline ◽  
Extracellular Fluid ◽  
Sodium Content ◽  
Sodium Balance ◽  
Sodium Retention ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Near Term ◽  
Total Sodium

Pregnant rats of two strains showed average net accumulation of approximately 83 mEq of sodium/kg of weight gain throughout gestation. Of the total sodium retention, 15, 23, and 62% occurred in each successive third of gestation. Analysis of postpartum sodium balance and of fetal sodium content at term indicated that there was no net accumulation of sodium in the tissues of the dams. Near term, rats given isotonic saline solution showed diminished ability to excrete the administered water in the urine, but showed no impairment in sodium excretion. Serum sodium concentrations were slightly decreased and serum osmolalities were significantly decreased in comparison to values for nonpregnant rats. At term the pregnant rats had greater extracellular fluid volumes than did nonpregnant controls.

Urinary excretion of water, sodium, and total solutes by the pregnant rat

1963 ◽  
Vol 204 (4) ◽  
pp. 563-567 ◽  
Author(s):  
I. J. Lichton
Keyword(s):  
Filtration Rate ◽  
Saline Solution ◽  
Isotonic Saline ◽  
Tubular Reabsorption ◽  
Sodium Pentobarbital ◽  
Stomach Tube ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Conscious Rats ◽  
Anesthetized Rats

Excretory responses were studied before mating and at intervals during gestation in conscious rats given isotonic saline solution by stomach tube and in sodium pentobarbital-anesthetized rats infused with saline intravenously. In conscious rats excretion of water and solutes in relation to the dose given was enhanced on day 13 of gestation in comparison to before mating and significantly depressed on day 20. Depressed excretion of water on day 20 was proportional to the number of newborn pups and was accompanied by equally depressed excretion of sodium and total solutes. In anesthetized rats excretion of water, sodium, and total solutes was also significantly depressed on day 20 of gestation while glomerular filtration rate was only slightly depressed. Tubular reabsorption of water and solutes was significantly higher in 20-day pregnant rats than in nonpregnant rats. It is suggested that this increase in tubular reabsorption may represent a response to depletion of maternal extracellular fluids by the growing fetuses.

Quantitative relationship of renal glucose and sodium reabsorption during ECF expansion

1975 ◽  
Vol 229 (1) ◽  
pp. 66-71 ◽  
Author(s):  
Higgins JT ◽  
AE Meinders
Keyword(s):  
Proximal Tubule ◽  
Isotonic Saline ◽  
Extracellular Fluid ◽  
Quantitative Relationship ◽  
Ringer Solution ◽  
Sodium Balance ◽  
Sodium Reabsorption ◽  
Coupled Transport ◽  
Appearance Time ◽  
Glucose Reabsorption

To investigate the quantitative relationship between glucose and sodium reabsorption during extracellular fluid (ECF) expansion and to examine the possible contribution to glucosuria of passive diffusion of glucose from peritubular blood to tubular fluid, renal clearance studies were carried out in dogs. It was found that ECF expansion with isotonic saline or Ringer solution causes a decrease in the maximal rate of glucose reabsorption (TmGlc), which is inversely and linearly related to fractional sodium excretion (FENa) over a range from less than 1% more than 25% FENa (r equals -0.394, P less than 0.001). A continuous relationship between TmGlc and FENa could be demonstrated as the ECF was expanded in individual animals as well as in pooled data. Infusion of albumin solution to preferentially expand the plasma volume and decrease proximal tubular sodium reabsorption produced a 24% fall in TmGlc suggesting that the proximal tubule is the site of interrelated glucose and sodium reabsorption. After pulse injections into the renal artery, [14-C]glucose and insulin had the same appearance time in the urine, thus failing to demonstrate diffusion of glucose from blood into the tubule in saline-loaded dogs as well as in dogs in normal sodium balance. It is suggested that ECF expansion exerts its effect on glucose reabsorption by inhibiting the coupled transport of glucose and sodium across the epithelium of the renal proximal tubule.

Role of renal nerves in renal sodium retention of nephrotic syndrome

1989 ◽  
Vol 256 (5) ◽  
pp. F823-F829 ◽  
Author(s):  
P. J. Herman ◽  
L. L. Sawin ◽  
G. F. DiBona
Keyword(s):  
Nephrotic Syndrome ◽  
Renal Denervation ◽  
Sodium Content ◽  
Vehicle Control ◽  
Dietary Sodium ◽  
Sodium Balance ◽  
Renal Nerves ◽  
Sodium Retention ◽  
Edema Formation

To define the role of the renal nerves in the renal sodium retention of the nephrotic syndrome, experiments were conducted in rats given adriamycin to produce nephrotic syndrome. All rats developed proteinuria and hypoalbuminemia and exhibited edema formation. Adriamycin-injected nephrotic rats were subjected to bilateral renal denervation (ADRIADNX) or sham renal denervation (ADRIASHAM). Rats injected with adriamycin vehicle were subjected to bilateral renal denervation (DNX) or sham renal denervation (SHAM). Metabolic balance studies were carried out in all rats beginning on the 8th day after bilateral or sham renal denervation. Dietary sodium content was 210 meq/kg Na on days 8-12 and days 24-26 and was 10 meq/kg Na on days 13-23. Nephrotic rats demonstrated significantly greater overall (19 days) cumulative sodium balance than vehicle control rats, ADRIASHAM 8.47 +/- 0.81 vs. SHAM 5.74 +/- 0.34 meq Na, P less than 0.01. Bilateral renal denervation did not significantly affect overall cumulative sodium balance in the vehicle control rats, DNX 6.15 +/- 0.71 vs. SHAM 5.74 +/- 0.34 meq Na. However, bilateral renal denervation significantly decreased overall cumulative sodium balance in the nephrotic rats, ADRIADNX 6.59 +/- 0.56 vs. ADRIASHAM 8.47 +/- 0.81 meq Na, P less than 0.01. Results indicated that the increased renal sodium retention characteristic of nephrotic syndrome is dependent, in large part, on increased efferent renal sympathetic nerve activity.

Effects of Temperature on Branchial Sodium-Exchange and Extrusion Mechanisms in the Seawater-Adapted Flounder Platichthys Flesus L

1972 ◽  
Vol 56 (3) ◽  
pp. 565-585
Author(s):  
J. MAETZ ◽  
D. H. EVANS
Keyword(s):  
Sodium Content ◽  
Sodium Balance ◽  
Irreversible Damage ◽  
Simple Diffusion ◽  
Sodium Efflux ◽  
Temperature Changes ◽  
Platichthys Flesus ◽  
Sodium Load ◽  
Sodium Extrusion ◽  
Total Sodium

1. The effects of short-term and long-term temperature changes on the branchial components of sodium balance have been studied in the seawater-adapted flounder Platichthys flesus. 2. When fish adapted to 6°C are compared with fish adapted to 16°C a disturbance of sodium balance is observed; while the plasma level of sodium remains constant, an increased internal sodium space can be demonstrated isotopically. Increase of the muscle sodium content accounts for only a small part of the extra sodium content of the fish. The increased sodium load is the result of an impairment of the sodiumextrusion mechanism in the gills, and is demonstrated by the disappearance of the Na/K exchange activity of the gills. The passive sodium fluxes (by simple diffusion or exchange-diffusion) decrease only twofold. 3. Abrupt temperature changes in the 6-21°C temperature range are followed by instantaneous and reversible changes of the total sodium efflux (Q10 = 2), of the sodium leak observed after transfer into fresh water (Q10 = 1.7) and of the Na/Na exchange (Q10 = 2). The Na/K exchange, which corresponds presumably to the active sodium extrusion mechanism, shows in contrast a much greater temperature dependence (Q10 = 6). The total sodium efflux follows the Arrhenius relation between 6 and 21°C. 4. Abrupt transfer to higher temperatures (23-26 °C) produces irreversible damage to the transport system. 5. No compensatory acclimatization of the flux rates is observed during adaptation in the 6 °C environment. 6. The biological, physiological, ecological as well as biophysical implications of these findings are discussed. Particular emphasis is given to the problem of gill haemo-dynamics.

Electrolyte Changes in Patients with Subarachnoid Haemorrhage

1972 ◽  
Vol 42 (2) ◽  
pp. 179-187 ◽  
Author(s):  
I. M. James
Keyword(s):  
Blood Flow ◽  
Subarachnoid Haemorrhage ◽  
Renal Blood Flow ◽  
Renal Plasma Flow ◽  
Extracellular Fluid ◽  
Plasma Potassium ◽  
Respiratory Alkalosis ◽  
Sodium Balance ◽  
Sodium Retention ◽  
Arterial Blood

1. After spontaneous subarachnoid haemorrhage in man there is an acute rise in arterial blood pressure. Sodium balance studies were carried out on sixty-four patients with this syndrome and marked sodium retention was found to occur which did not appear to be correlated with a low glomerular filtration rate nor with any consistent change in aldosterone excretion. 2. Effective renal plasma flow was measured by p-aminohippurate clearance in twenty-four patients and renal blood flow calculated from the haematocrit. Renal blood flow was found to be significantly depressed during the first week of the illness. The possibility that the sodium retention was due to changes in proximal tubular reabsorption secondary to alterations in intrarenal pressure is discussed. 3. No change in potassium balance was found despite the frequent occurrence of hypokalaemia. The depression of plasma potassium was closely related to the degree of respiratory alkalosis. Since respiratory alkalosis has been shown in animals to occasion a shift of potassium from the extracellular fluid into the cells, it is postulated that a similar change occurs after subarachnoid haemorrhage in man.

Effects of ligation of uterine veins in pregnant rats

1963 ◽  
Vol 205 (1) ◽  
pp. 201-202 ◽  
Author(s):  
I. J. Lichton
Keyword(s):  
Isotonic Saline ◽  
Extracellular Fluid ◽  
Venous Drainage ◽  
Pregnant Rats ◽  
Saline Loading

Uterine veins were ligated on day 14 of gestation in 24 rats; this procedure ensures drainage of uterine blood via the ovarian veins only. Eighteen sham-operated rats served as controls. The uterine vein-ligated rats showed no tendency to accumulate excessive extracellular fluid during gestation, and they excreted more water and solute in response to isotonic saline loading at term than did the controls. These results afford no evidence to strengthen the hypothesis that high implantation with consequent uterine venous drainage predominantly through the ovarian veins is a cause of human pre-eclampsia-eclampsia.

Foetal and maternal plasma adrenaline and noradrenaline concentrations in the late pregnant rat: effects of intra-uterine isotonic saline or uterine handling

1981 ◽  
Vol 96 (4) ◽  
pp. 541-545 ◽  
Author(s):  
C. Legrand ◽  
J. P. Maltier
Keyword(s):  
Isotonic Saline ◽  
Maternal Plasma ◽  
Sham Operation ◽  
Plasma Catecholamine ◽  
Plasma Samples ◽  
Saline Injection ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Plasma Adrenaline ◽  
Prolonged Effect

Abstract. The catecholamines adrenaline (A) and nor-adrenaline (NA) were determined in plasma samples of late pregnant rats and rat foetuses using a radioenzymatic procedure. In maternal plasma of control rats, values of A were stable during the last three days of gestation (between 5.64 and 6.90 ng/ml) whereas NA values increased just before parturition (+ 70%) and on day 23 post-coitum NA was the main plasma catecholamine. In foetal plasma of control rats, values of A and NA were constant during the last three days of gestation and A was always higher than NA. For both catecholamines, values in foetal plasma were lower than in maternal plasma. Blood of rats injected with isotonic saline into the uterus on day 21 of gestation contained 24 h and 48 h later about 2–3 times more A, and no more NA, than blood of control rats. In foetal plasma the levels of both catecholamines especially of NA were greatly increased after the handling of the uterus or the intra-uterine isotonic saline injection. Both treatments had the same prolonged effect upon A and NA values in foetal plasma. There is no increase of A and NA in maternal and foetal plasma after sham-operation. Although the values of plasma A and NA were high in control rats because blood sampling was carried out under stressful conditions, these results showed that handling of the uterus or injection of intrauterine isotonic saline was a severe aggression for the mother and foetus.

Effects of sinoaortic baroreceptor denervation on depletion-induced salt appetite

1994 ◽  
Vol 267 (4) ◽  
pp. R1043-R1049 ◽  
Author(s):  
R. L. Thunhorst ◽  
S. J. Lewis ◽  
A. K. Johnson
Keyword(s):  
Aortic Arch ◽  
Saline Solution ◽  
Carotid Sinus ◽  
Extracellular Fluid ◽  
Sodium Balance ◽  
Salt Appetite ◽  
Sodium Depletion ◽  
Neural Input ◽  
Normal Expression ◽  
Negative Balance

This study examined the effects of denervation of the carotid sinus and aortic arch baroreceptors on sodium depletion-induced salt appetite in rats. Depletion of extracellular fluid began with two injections of furosemide (10 mg/kg sc), 30 min apart, and removal of all ambient sodium from the cages. Water and sodium-deficient chow were available overnight. The next morning, access to 0.3 M NaCl was provided, and intakes of water and saline were measured every 30 min for 2 h and again at 24 h. Three such tests were administered. Groups of sham and sinoaortic baroreceptor-denervated (SAD) rats had equivalently negative water and sodium balances before access to saline the next morning. Sham-denervated rats drank sufficient saline in 2 h to achieve positive sodium balance and subsequently ingested sodium in excess of need for another 22 h. SAD rats drank half as much saline as sham-denervated rats by 2 and 24 h and remained in negative balance at 2 h. Sham-denervated rats increased their intakes of saline solution with repeated tests, but SAD rats did not. These findings suggest that arterial baroreceptors provide critical neural input for the normal expression of salt appetite.

Sodium balance during pregnancy in the rat

1980 ◽  
Vol 239 (1) ◽  
pp. R143-R148 ◽  
Author(s):  
S. E. Churchi-l ◽  
H. H. Bengele ◽  
E. A. Alexander
Keyword(s):  
Time Course ◽  
Sodium Intake ◽  
Sodium Balance ◽  
Sodium Retention ◽  
Third Trimester ◽  
Pregnant Rats ◽  
Products Of Conception ◽  
Inulin Space ◽  
And Control ◽  
Sodium And Potassium

The purpose of this study was to quantitate sodium balance during gestation in the rat (3 wk) to determine the time course of salt retention and to define the distribution of the retained salt. We have found that while sodium retention appears to begin during the 2nd wk, the bulk of retention occurs during the 3rd wk when the rat excretes only 67% of that ingested. Compared to that of nonpregnant, control rats, net retention for all of gestation was 9.8 meq. Despite a significantly higher sodium intake in pregnant rats, neither urinary nor fecal sodium excretion was different in pregnant and control rats. Fifty-nine percent of the retained sodium was found in the products of conception. Inulin space was increased by term from 19.7 to 25.4% of nonconceptus body weight. In pregnant rats a net retention of 6.3 meq of potassium was noted, 55% of which was found in the products of conception. We conclude that the rat retains sodium and potassium during pregnancy, predominantly in the third trimester. Over half of these salts are found within the conceptus products.

PROGESTERONE IN THE UTERUS

1974 ◽  
Vol 77 (1) ◽  
pp. 160-170 ◽  
Author(s):  
D. Egert ◽  
H. Maass
Keyword(s):  
Extracellular Fluid ◽  
Uterine Tissue ◽  
Rat Uterus ◽  
Pregnant Rats ◽  
Pregnant Rat

ABSTRACT Radio-metabolites of progesterone and progesterone itself were found in the uteri of intact pregnant rats 20 min after injection of [1,2-3H]progesterone. However, after evisceration and removal of the foeto-placental unit, and following injection of the labelled steroid, the progesterone content in the extract from the pregnant rat uterus markedly increased while the metabolite levels correspondingly decreased. An analogous change was observed in the plasma. Thus it appears probable that progesterone is not metabolized in the uterus of pregnant rats, and that metabolites found in this tissue originate predominantly in the foetoplacental system and appear in the plasma and extracellular fluid present in the uterine tissue.

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