Degree Of Volume Expansion Research Articles

Synthesis of silicon carbide nanoparticles from amorphous carbon: Based on the domain structure of electrically calcined anthracite

Based on the domain theory, the domain structure of electrically calcined anthracite was studied for the first time. The carbon microstructure of the electrically calcined anthracite was analyzed using atomic force microscopy (AFM). The analysis revealed that the carbon microstructure comprised microdomains with particle sizes below 30 nm and domains with particle sizes below 200 nm. In addition, non-graphitizable carbon structures formed by partial microdomain and domain structures were difficult to grow. Thus, we successfully synthesized novel β-type silicon carbide (β-SiC) nanoparticles with larger particle sizes below 200 nm and smaller particle sizes below 60 nm using a non-graphitizable carbon composed of carbon nanoparticles as the main raw material. Through calculation and analysis, the synthesis mechanism revealed that due to the presence of highly reactive interfacial regions between the domains of electrically calcined anthracite, silicon first diffused to the highly reactive interface between the domains of electrically calcined anthracite and reacted with the highly active carbon atoms in it to form silicon carbide, resulting in a certain degree of volume expansion. The volume expansion led to the cracking and dispersion of the domains, which further led to mutual diffusion and reaction within the exfoliated domains to generate SiC nanoparticles. And the non-exfoliated SiC nanoparticles generated at the reaction interface on the surface of electrically calcined anthracite were observed by the AFM.

Effect of pre-treatment and oil popping conditions on quinoa popping quality

Abstract Quinoa is a pseudocereal having outstanding nutritional profile and health-promoting biofunctional compounds. It is able to pop into an affordable, crispy, and flavourful ready-to-eat snack by conventional oil-popping method. Oil-popping is the process of frying grains in hot oil for a short time to induce vapour-driven expansion of grains. The effects of process variables on oil-popping quality of quinoa were evaluated. The conditions of processing were optimised using Response Surface Methodology. The grains (10 g) were hydrated by adding 0.1–0.3 mL of water containing a varying salt concentration of 0–1%, w/w and popped in coconut oil maintained at a popping temperature of 200–240 °C for a popping time of 10–30 s. The developed popped quinoa was analysed for popping quality indices. It was found that the increase in popping temperature, popping time, and salt concentration, and decrease in moisture level significantly decreased bulk density but increased popping yield (% popped grains), expansion ratio (degree of volume expansion), and flake size (average kernel size) of popped quinoa. Overall acceptability of popped quinoa in terms of sensory attributes was positively correlated with popping temperature and popping time. The optimised variables generated a popping yield of 75.56%, expansion ratio of 3.07, flake size of 11.58 mm3, bulk density of 0.29 g mL−1, and overall acceptability score of 8.40. A threefold expansion and a fair popping yield obtained from oil-popped quinoa offer a significant potential to generate profit for manufacturers.

Changes of the band structure of Mg2Si induced by interstitial doping with nonmetallic elements

The electronic structures and the densities of states of Mg8Si4X1 were calculated by using density functional theory, where semiconducting Mg2Si and a nonmetallic element, X, form interstitial alloys. When X is an inert gas element, the electronic structure is basically the same as that of Mg8Si4, but the bandgap increases (X = He or Ne) or decreases (X = Ar) depending on the degree of volume expansion caused by the interstitial alloying. In the case of X = electronegative element (O, F, or Cl), X works as an electron acceptor, which causes the transition of Mg2Si from an intrinsic semiconductor to a p-type semiconductor. This is also the case for X = H. When the electronegativity of X is intermediate (X = C, Si, N, P, or S), the bandgap at the R point of the reciprocal lattice of Mg8Si4 becomes negligible. When X = B, a transition to an n-type semiconductor is predicted as in the case of doping with electropositive metal elements such as Li and Al, but the bandgap at the R point of the reciprocal lattice of Mg8Si4 becomes negligible, as in the case of elements with intermediate electronegativities.

P4522Intravascular volume expansion mitigates the impact of impaired renal function and associated clinical outcomes in chronic heart failure

Abstract Background/Introduction Intravascular volume is regulated by the kidneys but the interconnection of the extent of volume expansion with renal function and outcomes in patients with chronic HF has not been assessed. Therefore, we evaluated how GFR-defined renal function and HF-related clinical outcomes are impacted by the relative extent of intravascular volume expansion. Our hypothesis was that greater rather than lesser volume expansion would be protective of worse renal function and contribute to better clinical outcomes than mild-moderate volume expansion. Purpose Assess the impact of quantitated intravascular volume expansion on heart failure (HF) outcomes in relation to renal function in post-hospital clinically determined “euvolemic” chronic HF patients. Methods Blood volume (BV) was prospectively measured in 87 HF patients considered clinically “euvolemic” post-diuresis at the time of hospital discharge using a standardized radiolabeled albumin indicator-dilution technique (Daxor Corp., NY, NY). A volume cut-point of ≥+25% above normal expected BV was used to define the greater degree of volume expansion from more mild-moderate expansion. These volume subgroups were then stratified by cohort median eGFR (46 mL/min/1.73m2) and analyzed for 1-year outcomes of HF-related mortality or 1st re-hospitalization using the Kaplan-Meier method. Results Volume expansion ≥+25% was demonstrated in 53% of the cohort at the time of hospital discharge despite hospital diuretic therapy. In this subgroup over 1.0 year of follow-up the risk for the composite outcome was significantly lower than in the group with mild-moderate volume expansion (Log-Rank p=0.017). Further, in the clinical setting of greater volume expansion, worse renal function with eGFR below the cohort median (<46 mL/min/1.73m2) was not associated with increased risk for the composite end-point (Figure). In contrast, low eGFR in the presence of mild-moderate volume expansion stratified risk and was associated with worse outcome relative to a higher eGFR above the median (Figure). Figure 1 Conclusions In post-hospital chronic HF patients significant intravascular volume expansion is common, and importantly the extent of BV expansion impacts outcomes including HF-related mortality. However, greater rather than lesser volume expansion appears to favorably mitigate the impact of worse renal function (low eGFR), while normal or mild-moderate expansion does not spare the impact of worse renal function on outcomes. Thus, a favorable degree of volume expansion appears to balance the risks of worse renal function. Volume-kidney interconnections are complex with volume status modulating the impact of impaired renal function on outcomes in chronic HF. Acknowledgement/Funding None

Super‐Hydrated Zeolites: Pressure‐Induced Hydration in Natrolites

High-pressure synchrotron X-ray powder diffraction studies of a series of alkali-metal-exchanged natrolites, A16Al16Si24O80·nH2O (A=Li, K, Na, Rb, and Cs and n=14, 16, 22, 24, 32), in the presence of water, reveal structural changes that far exceed what can be achieved by varying temperature and chemical composition. The degree of volume expansion caused by pressure-induced hydration (PIH) is inversely proportional to the non-framework cation radius. The expansion of the unit-cell volume through PIH is as large as 20.6% in Li-natrolite at 1.0 GPa and decreases to 6.7, 3.8, and 0.3% in Na-, K-, and Rb-natrolites, respectively. On the other hand, the onset pressure of PIH appears to increase with non-framework cation radius up to 2.0 GPa in Rb-natrolite. In Cs-natrolite, no PIH is observed but a new phase forms at 0.3 GPa with a 4.8% contracted unit cell and different cation-water configuration in the pores. In K-natrolite, the elliptical channel undergoes a unique overturn upon the formation of super-hydrated natrolite K16Al16Si24O80·32H2O at 1.0 GPa, a species that reverts back above 2.5 GPa as the potassium ions interchange their locations with those of water and migrate from the hinge to the center of the pores. Super-hydrated zeolites are new materials that offer numerous opportunities to expand and modify known chemical and physical properties by reversibly changing the composition and structure using pressure in the presence of water.

Detailed study of the ring‐opening metathesis polymerization of norbornene bearing a five‐ or six‐membered ring cyclic carbonate along with volume expansion

AbstractThe ring‐opening metathesis polymerization (ROMP) of norbornene derivatives bearing five‐ or six‐membered cyclic carbonate (2 or 3) was carried out with a typical ruthenium catalyst [bis(tricyclohexylphosphine)benzylidene ruthenium(IV) dichloride], the so‐called first‐generation Grubbs catalyst, under various reaction conditions, to smoothly obtain the corresponding polyalkenamers (5 and 6) along with volume expansion. The number‐average molecular weights (Mn's), 10% weight loss decomposition temperatures, glass‐transition temperatures (Tg's), and volume expansion ratios of the resulting products depended on the polymerization conditions. The degree of volume expansion was mainly affected by Mn, Tg, and the cis/trans configuration of the exocyclic double bonds of the resulting polymers. The volume expansion was confirmed to specifically occur during the polymerization of the monomer bearing cyclic carbonate moieties, and similar ROMPs of monomers without cyclic carbonate, such as norbornene itself, the monomer 5,5‐bis(methoxymethyl)bicyclo[2.2.1]hept‐2‐ene, and the monomer endo‐N‐methylbicyclo[2.2.1]hept‐5‐ene‐2,3‐dicarboxylimide, proceeded along with volume shrinkage. Furthermore, an investigation of another type of polymerization, a vinyl‐type one, of monomer 2 suggested that the volume expansion specifically took place in the ring‐opening type of polymerization. In addition, the Sc(OTf)3‐mediated cationic ring‐opening reaction of the cyclic carbonate moiety of polyalkenamer 5 smoothly proceeded along with volume expansion or nearly zero volume shrinkage to yield the corresponding networked polymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 395–405, 2006

High Dose Human Serum Albumin for the Treatment of Acute Ischemic Stroke: A Safety Study

In animal models of focal cerebral ischemia, albumin infusions at doses ranging from 0.6 to 2.5 g/kg are neuroprotective. It is not known whether patients with stroke, often elderly and with underlying cardiovascular disease, can safely tolerate such degrees of volume expansion. Therefore, we retrospectively reviewed the safety of high-dose albumin treatment in patients with acute ischemic stroke. Within 24 hours of ischemic stroke onset, patients who received at least 0.7 g/kg albumin were identified by a review of medical records. Each albumin recipient was assigned two control patients, who received standard fluid management. Controls were matched by age, number of stroke risk factors, stroke severity, and stroke subtype. Medical records were reviewed for treatment-related adverse events, defined as cardiopulmonary complications and mortality. Thirty cases (mean age 62.9+/-11.4 years) and 60 controls (mean age 62.5+/-11.8 years) were identified between July 1999 and November 2001. The two groups were evenly matched. The mean dose of albumin infusion was 171 g (2.4 g/kg). Cardiopulmonary complications or death developed in 37% of cases and 18% of controls (p=0.056). Mortality was 7% in both groups. Multivariate regression analysis showed that a history of congestive heart failure and higher total albumin dose were independently associated with the occurrence of adverse events. Albumin treatment was associated with a nonsignificant trend toward increased cardiopulmonary adverse events. However, these adverse events did not result in excess mortality.

Hemodilution mediates changes in renal hemodynamics after acute volume expansion in rats.

The present study examined the factors responsible for triggering renal hemodynamic adjustments during acute volume expansion. The renal hemodynamic effects of graded volume expansion with 0.9% saline (Sal; 1, 2, and 4% of body wt), 7% BSA solution (0.35, 0.70, and 1.4% body wt), or whole blood from a donor rat (WBL; 0.35, 0.70, and 1.4% body wt) were compared in rats anesthetized with pentobarbital sodium. Neural influences on the kidney were eliminated by vagus nerves, baro/chemoreceptor afferents, and renal nerves section, and renal perfusion pressure was controlled at constant level (approximately 120 mmHg) throughout the experiments. In Sal- and BSA-expanded rats, renal blood flow (RBF) increased (Sal: 15, 40, 71%; BSA 17, 49, 107%) and renal vascular resistance (RVR) decreased in parallel with the degree of volume expansion (RVR: Sal 17, 31, 44%; and BSA: 15, 35, 54%). Renal hemodynamics remained unaltered after expansion with WBL. In rats expanded with Sal or BSA, correction of the fall of hematocrit restored RBF and RVR to control levels. Interference with tubuloglomerular feedback by uretheral obstruction had no effect on the decrease in RVR with Sal or BSA. Inhibition of the vascular tone by intrarenal papaverine infusion also did not alter the renal hemodynamic response to volume expansion with Sal or BSA. These findings suggest that the changes in renal hemodynamics after acute expansion are likely mediated by changes in rheologic properties of the blood rather than by changes in active vascular tone.

Cyclic carbonates, novel expandable monomers on polymerization

AbstractA variety of cyclic carbonates was shown to undergo volume expansion on polymerization. The degree of volume expansion, which was measured by the density gradient tube method, was ranging from 1.1% to 7.7%. The volume expansion was examined by assuming a change in molecular interaction such as dipole moment between monomer and polymer states.

Increased Plasma Level of Endothelin-1 in the Okamoto Spontaneously Hypertensive Rat

The objectives of this study were to determine plasma levels of endothelin (ET) in a genetic model of hypertension and in control rats during control conditions and in response to short-term volume expansion with saline. Okamoto spontaneously hypertensive rats (SHR) and control Wistar-Kyoto (WKY) rats were used in this study. One group of each strain served as control animals, and another group of each strain underwent volume expansion with saline (5% of body weight infused during a period of 30 minutes). The levels of ET-1 and ET-3 were measured in plasma by using a double-antibody radioimmunoassay. In the control groups of SHR and WKY rats, plasma ET-1 levels were 72.5 +/- 14.9 pg/ml (N = 8) and 40.2 +/- 7.5 pg/ml (N = 12), respectively (P < 0.05). In the volume-expanded SHR group (N = 8), the plasma ET-1 level was 45.5 +/- 11.1 pg/ml (approximately 37% less than that of the control SHR group), whereas it was 40.6 +/- 10.2 pg/ml in the volume-expanded group of WKY rats (N = 10) (almost identical to that of the control WKY group). Plasma levels of ET-3 were similar in control and in volume-expanded groups of SHR and WKY rats. These data show that basal levels of plasma ET-1 are significantly higher in the SHR than in the WKY rat.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of dopamine receptor blockade on natriuresis is dependent on the degree of hypervolemia

A number of different physiological factors and systems have been suggested to be responsible for the natriuretic effect following acute isotonic volume expansion (VE). The variation in suggestions may depend on the prevailing status of the systems governing fluid and electrolyte balance before VE, on the expansion medium and on the rate and degree of VE. A study was performed to determine whether the previously documented attenuating effect of dopamine receptor blockade on natriuresis induced by VE is dependent on the degree of hypervolemia. Anesthetized rats were pretreated with the dopamine receptor blockers haloperidol (1 mg.kg-1 body weight, i.p.), SCH 23390 (30 micrograms.hr-1.kg-1 i.v.) or vehicle and then subjected to VE at 2, 5 or 10% of body weight per hour. VE at 2, 5 and 10% increased sodium excretion in vehicle-pretreated animals 6-, 29- and 130-fold, respectively. In the haloperidol-pretreated animals the natriuretic response (accumulated sodium excretion) to VE was attenuated by 67% (P less than 0.05), 46% (P less than 0.05) and 22% (NS) at the three degrees of expansion, respectively. The corresponding attenuation in SCH 23390-treated animals were 60% (P less than 0.05), 56% (P less than 0.05) and 19% (NS), respectively. The gradual decrease in attenuation indicates that at varying degrees of hypervolemia, different physiological systems contribute differently to the renal natriuretic response. The dopamine system seems to be relatively more important in promoting natriuresis at the lower (physiological) range of hypervolemia whereas in the high range other factors have a greater impact.

Effects of atrial appendectomy on circulating atrial natriuretic factor during volume expansion in the rat.

This study examined the changes in the circulating level of endogenous atrial natriuretic factor during diuresis and natriuresis produced by acute volume expansion in anesthetized rats with either bilateral atrial appendectomy (n = 9) or sham operation (n = 9). Following control measurements in the sham-operated rats, 1% body weight volume expansion with isotonic saline produced an increment in urinary sodium excretion of over 4 mueq/min (P less than 0.05) while urine volume increased by more than 20 microliter/min (P less than 0.05). These responses were associated with a significant increase in immunoreactive plasma atrial natriuretic factor from a baseline value of 82 +/- 10 pg/ml to a level of 120 +/- 14 pg/ml (P less than 0.05). In contrast, in the group of rats with bilateral atrial appendectomy an identical degree of volume expansion increased urinary sodium excretion and urine volume by only 0.61 mueq/min (P less than 0.05) and 3.07 microliter/min (P less than 0.05), respectively. In this group, immunoreactive plasma atrial natriuretic factor remained statistically unchanged from a control value of 70 +/- 12 pg/ml to a level of 82 +/- 16 pg/ml (P greater than 0.05). Comparison of the two groups indicates that the natriuresis, diuresis, and plasma atrial natriuretic factor levels during volume expansion were significantly reduced in the rats with bilateral atrial appendectomy. No differences in mean arterial pressure and heart rate were observed between the two groups. These data demonstrate that removal of both atrial appendages in the rat attenuated the release of atrial natriuretic factor during volume expansion; and this effect, in turn, was associated with a reduction in the natriuretic and diuretic responses.

Differential effect of salt loading on sodium and lithium excretion in Dahl salt-resistant and -sensitive rats.

Fractional excretion of lithium, as a marker for proximal sodium reabsorption, was determined in normotensive Dahl S rats (susceptible to NaCl hypertension) and Dahl R rats (resistant to NaCl hypertension) before and following an acute sodium load. Baseline mean arterial pressures, inulin clearances, sodium excretion rates, and fractional lithium clearances were not different between the R and S rats. Following the salt loading and despite similar mean arterial pressures and degree of volume expansion, the glomerular filtration rate, urinary flow rates, and absolute sodium excretion rates were greater in R than S rats. The fractional excretion of lithium was also greater in R than S rats. These data demonstrate that, at equal mean arterial pressures, Dahl S rats have a reduced capacity for sodium excretion, and that this defect is present prior to the development of hypertension. Furthermore, the observation that these animals also have a lower fractional lithium excretion during volume expansion suggests that salt loading reduces proximal tubule reabsorption to a lesser extent in Dahl S than R rats. These data suggest that the subnormal sodium and water excretion observed after sodium loading in S rats may be partially due to an abnormality in proximal tubule sodium handling.

Enhancement of sodium excretion by substance P during saline loading in the canine puppy.

Summary: Saline loading in puppies results in an attenuated natriuresis when compared to the normal response by adult animals to the same degree of volume expansion. To characterize an eventual role for kinins in the diuretic response by puppies to saline loading, two experimental protocols were constructed to evaluate the effect of substance P infusion during baseline hydration and acute saline loading. Low dose (10 ng·kg−1·min−1) infusion of substance P during basal conditions did not affect urine flow, sodium excretion or glomerular filtration rate (GFR). The addition of saline loading to the ongoing low dose infusion of substance P produced an increase in urine flow from 3.73 to 12 μ l·min−1·g−1 kidney weight and resulted in a marked increase in urinary sodium excretion from 110 to 851 μ Eq·min−1·g−1 kidney weight. These increases in urine flow and urinary sodium excretion during low dose substance P infusion were significantly greater than those observed during saline loading alone. No significant effect on GFR was observed during either saline loading alone or low dose substance P during saline loading. In Protocol II, the infusion of low dose substance P during an ongoing saline load enhanced diuresis and natriuresis to a greater extent than those receiving only a saline load without affecting GFR. The high dose infusion of substance P (100 ng·kg−1·min−1) during baseline hydration resulted in a natriuresis and diuresis that persisted during the addition of saline despite a significant fall in GFR. Saline loading alone resulted in increased urinary kallikrein activity and the infusion of substance P (10 ng·kg−1·min−1) increased urinary kallikrein activity even further. A significant positive correlation between urinary sodium excretion and urine kallikrein activity was found (r = 0.91, P < 0.01).

Effect of medullary tonicity on urinary sodium excretion in the rat.

In previous reports from this laboratory we have suggested that a reduction in medullary tonicity decreases the thin ascending loop of Henle sodium reabsorption and is in part responsible for the magnitude for the natriuresis accompanying 10% body weight Ringer loading. According to this postulate, one would expect that the medullary washout associated with water diuresis would also result in a natriuresis, but this does not occur. It is possible, however, that increased delivery from the proximal tubule is necessary to demonstrate an effect of medullary tonicity on urinary sodium excretion. Micropuncture studies were designed to test that possibility by increasing distal delivery by 2% Ringer loading in animals with and without reduced medullary tonicity. In an initial series of experiments the alpha-adrenergic agonist clonidine was used to induce a water diuresis. When given alone, this agent caused a marked decrease in urine osmolality and an increase in urine flow rate but had no effect on proximal reabsorption in either superficial or juxtamedullary nephrons, and did not alter urinary sodium excretion. Volume expansion with 2% body weight Ringer solution resulted in a significant fall in proximal reabsorption and a trivial increment in sodium excretion. When this same degree of volume expansion was conferred on animals undergoing a water diuresis, a marked increase in absolute and fractional sodium excretion occurred. In a second group of studies medullary tonicity was reduced in the left kidney only by removal of the left ureter 1 h before micropuncture. When these animals were infused with 2% body weight Ringer solution, proximal reabsorption was decreased in juxtamedullary nephrons, and a marked increase in sodium excretion was observed only from the left kidney. Finally, the effect of water diuresis on fractional sodium delivery to the early and late distal tubule of superficial nephrons during 2% Ringer loading was evaluated. Delivery to both of these sites was comparable after 2% Ringer loading alone and during 2% Ringer loading plus water diuresis. From these data, we conclude that medullary tonicity does influence renal sodium handling but that this effect is manifest in the final urine only under conditions in which proximal reabsorption is decreased. The data also suggest that this effect is limited to juxtamedullary nephrons and is probably localized to the thin ascending limb of the loop of Henle.

Sodium and chloride transport along the inner medullary collecting duct: effect of saline expansion.

The effect of volume expansion on inner medullary collecting duct (IMCD) sodium transport remains controversial. Studies employing micropuncture of the IMCD base and tip were interpreted to demonstrate enhanced sodium and chloride reabsorption. Data obtained by microcatheterization evaluating only sodium transport revealed either no reabsorption or net addition. We have examined both sodium and chloride transport by microcatheterization. Volume expansion was comparable to the micropuncture studies: 0.9% saline equal to 10% body wt and then matched to urine flow. The fraction of filtered fluid, sodium, and chloride was analyzed as a function of IMCD length. In eight hydropenic rats 60% of the fluid, 71% of the sodium, and 48% of the chloride delivered to the IMCD was reabsorbed. In six volume-expanded rats no significant net reabsorption of fluid, sodium, or chloride was found. Accordingly, in contrast to the micropuncture results, we have demonstrated that net sodium chloride and fluid reabsorption are absent during volume expansion. We conclude that during volume expansion, fluid, sodium, and chloride excretion increase, in part, because of a reduction in net reabsorption along the IMCD. The degree of volume expansion does not account for the discrepancy between the two techniques.

Glycerol-induced myohemoglobinuric acute renal failure in the pregnant rat.

These studies examined the effects of the volume expansion and the enhanced activity of the renin-angiotensin system during pregnancy on the severity of glycerol-induced myoglobinuric acute renal failure (ARF) in the rat. Renal cortical renin content (RCRC) and plasma renin concentration (PRC) were measured during the first, second, and third weeks of pregnancy. There were no significant changes in RCRC during pregnancy, but PRC was significantly elevated by the third week (22 +/- 2 vs. 12 +/- 2 ng angiotensin I/ml/k, p less than 0.001), despite plasma volume expansion as assessed by changes in the hemotocrit (37.7 +/- 0.5 vs. 46.4 +/- 0.6%, p less than 0.001). Despite the elevated PRC, a significant reduction in the severity of ARF was seen during the third week of pregnancy, as assessed by both blood urea nitrogen and inulin clearance measurements. When a sustained natriuresis was superimposed earlier in pregnancy by saline drinking, significantly more protection against ARF was seen, but with less plasma volume expansion. These results suggest that the mechanism by which saline drinking confers protection may be independent of the degree of volume expansion but may be dependent upon the associated sustained natriuresis.

Dopamine-sodium relationship: is dopamine a part of the endogenous natriuretic system?

A possible role of DA as an endogenous natriuretic hormone was reviewed under three aspects: (1) its excretion in response to saline vs. albumin-induced volume expansion, (2) the origin of urinary free DA and (3) urinary free DA excretion in an unexplained salt-retaining condition, idiopathic edema. We have shown (1) that the urinary free DA excretion increase in response to saline is specifically related to salt and does not occur when the same degree of volume expansion is induced by albumin, (2) that this increase in free DA originates in the kidney and (3) that idiopathic edema patients excrete less free DA than control subjects. It is proposed that free DA originating in the kidney is a rather sal than volume-dependent endogenous natriuretic factor. Its deficiency may contribute to excessive sodium retention in idiopathic edema. However, DA is probably not the single natriuretic hormone but a part of a natriuretic system, components of which are other renal vasodilating and natriuretic substances such as prostaglandins and kallikrein-bradykinin.

Role of oxytocin in the natriuresis of extracellular volume expansion.

SummaryThe effect of extracellular volume expansion on the oxytocin levels in jugular blood and the influence of oxytocin infusion on sodium excretion as the degree of volume expansion was varied, were evaluated in 8 anesthetized dogs. Extracellular volume expansion was not associated by a simualtneous rise in blood levels of oxytocin in 5 of the 8 dogs studied. Oxytocin infusion did not enhance sodium excretion during a steady state volume expansion and was unable to prevent the fall in urinary sodium as volume expansion was falling. The results indicate that oxytocin does not play an important role in the natriuresis of extracellular volume expansion.