The Water and Electrolyte Metabolism of Free-Ranging and Captive White-Browed Scrubwrens, Sericornis-Frontalis (Acanthizidae), From Arid, Semi-Arid and Mesic Environments

1988 ◽  
Vol 36 (1) ◽  
pp. 29 ◽  
Author(s):  
SJ Ambrose ◽  
SD Bradshaw
Keyword(s):  
Sodium Intake ◽  
Coastal Dunes ◽  
Dietary Sodium ◽  
Sodium Balance ◽  
Turnover Rates ◽  
Water Turnover ◽  
Shark Bay ◽  
Ecological Implications ◽  
Free Ranging ◽  
Semi Arid

Seasonal variations in water and sodium turnover of resident populations of free-ranging Sericornis frontalis were measured at three sites in Western Australia ranging from arid, through semi-arid to mesic environments. Scrubwrens at all three sites maintained water and sodium balance despite the wide variation in environment. During winter at semi-arid Eyre, however, scrubwrens had a greatly increased dietary sodium intake resulting from the deposition of airborne oceanic salt over the coastal dunes. Scrubwrens at arid Hamelin had significantly lower water turnover rates (e.g. 1.3 ml 10 g-'d-') than those at Eyre and mesic Rockingham during hot, dry periods. The highest rates of water turnover were recorded at Rockingham during wet winters. We discuss the ecological implications of these results. In laboratory studies, scrubwrens from arid regions consumed NaCl solutions of up to 0.8 mol l-', compared with a maximum of only 0.6 ml l-' by scrubwrens from semi-arid and mesic regions. Shark Bay scrubwrens also had a much greater renal-concentrating ability which may be partially accounted for by the larger proportion of medullary tissue in the kidneys of these birds.

Hormonal responses to gradual changes in dietary sodium intake in humans

1989 ◽  
Vol 256 (6) ◽  
pp. R1171-R1175 ◽  
Author(s):  
G. A. Sagnella ◽  
N. D. Markandu ◽  
M. G. Buckley ◽  
M. A. Miller ◽  
D. R. Singer ◽  
...  
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Sodium Intake ◽  
Plasma Renin ◽  
Normal Subjects ◽  
Progressive Increase ◽  
Plasma Aldosterone ◽  
Dietary Sodium ◽  
Sodium Balance ◽  
Initial Increase ◽  
Hormonal Responses

The effects of gradual (50 mmol/day) increases in dietary sodium intake from 10 to 350 mmol/day on plasma atrial natriuretic peptide (ANP), aldosterone, and plasma renin activity (PRA) were studied in six normal subjects. With the increases in sodium intake there was a progressive increase in urinary sodium from 12.2 +/- 4.4 to 314.8 +/- 31.4 mmol/24 h; plasma ANP increased gradually from 9.9 +/- 1.1 to 23.3 +/- 2.2 pg/ml, with the increases being closely associated with the changes in cumulative sodium balance. Plasma aldosterone decreased significantly from 2,519.7 +/- 147.4 pmol/l on the 10 mmol/day to 1,393.3 +/- 125.4 pmol/l when the sodium intake was increased to 50 mmol/day and decreased further to 251.6 +/- 78.7 pmol/l by the end of the study. The changes in PRA paralleled those in plasma aldosterone with the exception of no significant change in plasma PRA within 24 h of the initial increase in sodium intake. This marked sensitivity in the responses of both the ANP and the renin-aldosterone system to small increases in sodium intake clearly points to their importance in the renal adaptations to alterations in dietary sodium intake.

scholarly journals Effects of AT1A receptor deletion on blood pressure and sodium excretion during altered dietary salt intake

2002 ◽  
Vol 283 (3) ◽  
pp. F447-F453 ◽  
Author(s):  
Amy J. Mangrum ◽  
R. Ariel Gomez ◽  
Victoria F. Norwood
Keyword(s):  
Blood Pressure ◽  
Salt Intake ◽  
Sodium Intake ◽  
Dietary Sodium ◽  
Sodium Balance ◽  
Wild Type ◽  
Compensatory Mechanisms ◽  
Wide Range ◽  
Blood Pressures ◽  
Pressure Natriuresis

The present study was performed to investigate the role of type 1A ANG II (AT1A) receptors in regulating sodium balance and blood pressure maintenance during chronic dietary sodium variations in AT1A receptor-deficient (−/−) mice. Groups of AT1A (−/−) and wild-type mice were placed on a low (LS)-, normal (NS)-, or high-salt (HS) diet for 3 wk. AT1A(−/−) mice on an LS diet had high urinary volume and low blood pressure despite increased renin and aldosterone levels. On an HS diet, (−/−) mice demonstrated significant diuresis, yet blood pressure increased to levels greater than control littermates. There was no effect of dietary sodium intake on systolic blood pressures in wild-type animals. The pressure-natriuresis relationship in AT1A (−/−) mice demonstrated a shift to the left and a decreased slope compared with wild-type littermates. These studies demonstrate that mice lacking the AT1A receptor have blood pressures sensitive to changes in dietary sodium, marked alterations of the pressure-natriuresis relationship, and compensatory mechanisms capable of maintaining normal sodium balance across a wide range of sodium intakes.

Chronic sodium loading augments natriuretic response to acute volume expansion in the preweaned rat

1995 ◽  
Vol 269 (1) ◽  
pp. R15-R22 ◽  
Author(s):  
D. G. Muchant ◽  
B. A. Thornhill ◽  
D. C. Belmonte ◽  
R. A. Felder ◽  
A. Baertschi ◽  
...  
Keyword(s):  
Volume Expansion ◽  
Sodium Intake ◽  
Somatic Growth ◽  
Sodium Concentration ◽  
Dietary Sodium ◽  
Sodium Balance ◽  
Urinary Flow ◽  
Adult Rats ◽  
High Sodium ◽  
Before And After

Positive sodium balance is necessary for normal somatic growth of the neonate, and the neonatal renal response to volume expansion (VE) is attenuated compared with the adult. To test the hypothesis that dietary sodium modulates the developmental response to VE, preweaned rats were artificially reared with either a normal (25 meq/l)- or high-sodium (145 meq/l) diet for 7-8 days and were compared with adult rats receiving normal or high sodium. Serum sodium concentration remained normal in adults on high sodium, whereas neonates became hypernatremic. Glomerular filtration rate (GFR), urinary flow (V), and urinary sodium (UNaV) were measured before and after acute saline VE (1% body wt). While remaining constant in preweaned rats, GFR increased > 50% in adult rats after VE (P < 0.05). High sodium intake augmented V and UNaV after VE but was not sustained in neonates as in adults. Plasma atrial natriuretic peptide (ANP) and guanosine 3',5'-cyclic monophosphate excretion (UcGMPV) were measured, and baseline UcGMPV was lower in preweaned rats receiving normal sodium but increased to levels similar to adult levels after VE. Postexpansion plasma ANP was higher in preweaned rats than in adult rats and was not affected by dietary sodium regardless of age. We conclude that the attenuated postexpansion natriuresis in the neonate is due in part to an adaptive response to limited sodium intake. However, neonatal compensation to increased sodium intake is incomplete and independent of plasma ANP.

Water and energy balance of the thorny devil Moloch horridus: is the devil a sloth?

1995 ◽  
Vol 16 (1) ◽  
pp. 47-54 ◽  
Author(s):  
S.D. Bradshaw ◽  
P.C. Withers
Keyword(s):  
Metabolic Rate ◽  
Turnover Rate ◽  
Weather Conditions ◽  
Energy Turnover ◽  
Water Turnover ◽  
Field Metabolic Rate ◽  
Free Ranging ◽  
The Devil ◽  
Western Australian ◽  
Semi Arid

AbstractRates of turnover of water, energy and sodium were measured for free-ranging thorny devils (Moloch horridus), which are myrmecophagous agamid lizards, in a semi-arid Western Australian habitat. There were significant differences in body water content and water turnover rate (WTR) measurements for cool, wet, average and hot periods, although the field metabolic rate (FMR) and sodium turnover (NaTR) rate did not differ significantly between weather conditions. The thorny devil had a substantially lower field WTR during dry periods (10-15 ml kg-1 d-1) than expected for semi-arid and arid lizards, although the WTR was higher in wet conditions (30-35 ml kg-1 d-1). The field metabolic rate of thorny devils (0.134 ml CO2 g-1 h-1) was only slightly less than that expected for a semi-arid/lizard (0.178 ml CO2 g-1 h-1), despite the apparently slothful nature of the thorny devil. The sodium turnover rate of the thorny devil (1.5-2.5 mmol kg-1 d-1) was within the range reported for other semi-arid/arid lizards. The field metabolic rate of the thorny devils suggests that they consume about 750 ants per day. The ratio of water to energy turnover measured for thorny devils in the field (0.11 ml H2O kj-1) was the same as that predicted from the composition of ants and their digestibility by thorny devils (0.11 ml H2O kj-1). However, the ratios of sodium-to-energy turnover (30 μmol Na+ kj-1) and sodium-to-water turnover (277 μmol ml H2O-1) were substantially higher than expected ratios (10 and 89 respectively).

scholarly journals Blood pressure and endocrine responses to changes in dietary sodium intake in cardiac transplant recipients. Implications for the control of sodium balance.

Circulation ◽  
1994 ◽  
Vol 89 (3) ◽  
pp. 1153-1159 ◽  
Author(s):  
D R Singer ◽  
N D Markandu ◽  
M G Buckley ◽  
M A Miller ◽  
G A Sagnella ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Sodium Intake ◽  
Dietary Sodium ◽  
Sodium Balance ◽  
Cardiac Transplant ◽  
Transplant Recipients

A Paradoxical Fall in Urine Dopamine Output When Patients with Essential Hypertension Are Given Added Dietary Salt

1984 ◽  
Vol 67 (1) ◽  
pp. 83-88 ◽  
Author(s):  
J. N. Harvey ◽  
I. F. Casson ◽  
A. D. Clayden ◽  
G. F. Cope ◽  
C. M. Perkins ◽  
...  
Keyword(s):  
Essential Hypertension ◽  
Sodium Intake ◽  
Statistical Significance ◽  
Dietary Sodium ◽  
Sodium Balance ◽  
Control Group ◽  
Dietary Salt ◽  
Salt Loading ◽  
Hypertensive Patients ◽  
Renal Sodium Handling

1. The effect of dietary sodium on the urine dopamine excretion of eight hypertensive patients and six matched controls was studied under metabolic balance conditions over a 2 week period during which dietary sodium intake was increased from 20 to 220 mmol/day. 2. The control group showed the expected increase in dopamine excretion in response to sodium but the hypertensive patients showed an initial fall followed by a return to baseline values. 3. Neither group showed a rise in blood pressure but the hypertensive patients showed a greater weight gain on salt loading, although this change was not significant. The cumulative sodium balance was greater and more prolonged in the hypertensive patients, although this difference also did not attain statistical significance. 4. This defect in dopamine mobilization may be important in relation to renal sodium handling by patients with essential hypertension.

The Effects of a Temperature-Determined Food-Supply on the Annual Activity Cycle of the Lesser Long-Eared Bat, Nyctophilus-Geoffroyi Leach, 1821 (Microchiroptera, Vespertilionidae)

1991 ◽  
Vol 39 (3) ◽  
pp. 263 ◽  
Author(s):  
WAH Ellis ◽  
TG Marples ◽  
WR Phillips
Keyword(s):  
Food Supply ◽  
Tritiated Water ◽  
Activity Cycle ◽  
Turnover Rates ◽  
Water Turnover ◽  
Lactating Females ◽  
Fat Level ◽  
Annual Activity ◽  
Ad Libitum ◽  
Free Ranging

Tritiated-water turnover rates for captive Nyctophilus geoffroyi were highest at 1031.3 mL L-1 day-1 for lactating females in January 1985 and lowest at 82.5 mL L-1 day-1 for females receiving a temperature-determined food supply in July 1985. Daily rates of water turnover were generally higher for males than females, and for bats receiving ad libitum food than for those receiving a controlled food supply throughout winter, indicating that food availability affects torpor in N. geoffroyi. Pre-winter fat deposition was more efficient under conditions of a temperature-determined food supply, where activity, weight and fat-level fluctuations of captive N. geoffroyi closely resembled those known for free-ranging temperate-zone microchiropterans.

Immunoreactive Substance P in Human Plasma: Response to Changes in Posture and Sodium Balance

1980 ◽  
Vol 59 (1) ◽  
pp. 75-77 ◽  
Author(s):  
H. J. Kramer ◽  
R. Düsing ◽  
H. Stelkens ◽  
R. Heinrich ◽  
J. Kipnowski ◽  
...  
Keyword(s):  
Substance P ◽  
Salt Intake ◽  
Sodium Intake ◽  
Plasma Concentrations ◽  
Mean Value ◽  
Dietary Sodium ◽  
Sodium Balance ◽  
Dietary Salt ◽  
Dietary Salt Intake ◽  
High Sodium

1. In healthy volunteers plasma concentrations of immunoreactive substance P were measured in response to changes in posture and dietary salt intake. 2. In 14 subjects plasma immunoreactive substance P was 168 ± 31 pmol/l when subjects were supine and 401 ± 51 pmol/l (P < 0.001) when they were ambulant. 3. Measurement of supine plasma immunoreactive substance P at 6 h intervals gave a mean value of 240 ± 39 pmol/l at 14.00 hours and a lowest value of 76 ± 9 pmol/l at 02.00 hours. 4. In eight healthy subjects plasma immunoreactive substance P rose only slightly from 169 ± 41 pmol/l, on a sodium intake ad lib., to 244 ± 45 pmol/l by day 4 of dietary sodium restriction (35 mmol/day) and significantly fell to 51 ± 20 pmol/l (P < 0.001) by day 4 of high sodium intake (350 mmol/day). 5. Although exogenous substance P was shown to be natriuretic in dog and rat, the present results do not favour a role of endogenous substance P as a circulating natriuretic factor in man.

Role of renal nerves in maintaining sodium balance in unrestrained conscious rats

1985 ◽  
Vol 249 (6) ◽  
pp. F819-F826 ◽  
Author(s):  
E. Fernandez-Repollet ◽  
C. R. Silva-Netto ◽  
R. E. Colindres ◽  
C. W. Gottschalk
Keyword(s):  
Blood Pressure ◽  
Renal Denervation ◽  
Sodium Intake ◽  
Plasma Renin ◽  
Dietary Sodium ◽  
Sodium Balance ◽  
Renal Nerves ◽  
Sodium Restriction ◽  
Low Sodium ◽  
Dietary Sodium Restriction

This study was designed to investigate the effects of bilateral renal denervation on sodium and water balance, the renin-angiotensin system, and systemic blood pressure in unrestrained conscious rats maintained on a normal- or low-sodium diet. Renal denervation was proven by chemical and functional tests. Both bilaterally denervated rats (n = 18) and sham-denervated rats (n = 15) maintained positive sodium balance while on a normal sodium intake. Both groups were in negative sodium balance for 1 day after dietary sodium restriction was instituted but were in positive sodium balance for the following 9 days. Systolic blood pressure was higher in sham-denervated (115 +/- 3 mmHg) than in denervated rats (102 +/- 3 mmHg) while on a normal diet (P less than 0.05) and remained so during sodium restriction. Plasma renin concentration (PRC) and plasma aldosterone concentration (PAC) were significantly diminished in the denervated rats during normal sodium intake (P less than 0.05). After dietary sodium restriction, PRC increased in both groups but remained significantly lower in the denervated rats (P less than 0.05). Following dietary sodium restriction, PAC also increased significantly to levels that were similar in both groups of rats. These results demonstrate that awake unrestrained growing rats can maintain positive sodium balance on a low sodium intake even in the absence of the renal nerves. However, efferent renal nerve activity influenced plasma renin activity in these animals.

Dietary Sodium Intake: A Determinant of Postprandial Plasma Sodium Concentration in the Dog

1982 ◽  
Vol 62 (5) ◽  
pp. 471-477 ◽  
Author(s):  
E. G. Schneider ◽  
Sarah D. Gleason ◽  
A. Zucker
Keyword(s):  
Sodium Excretion ◽  
Sodium Intake ◽  
Urinary Sodium Excretion ◽  
Sodium Concentration ◽  
Dietary Sodium ◽  
Sodium Balance ◽  
Plasma Sodium ◽  
Free Access ◽  
Potassium Excretion ◽  
Plasma Sodium Concentration

1. The effect of dietary sodium intake on pre-and post-prandial plasma sodium concentrations and on the pattern of sodium and potassium excretion was determined in conscious female dogs, who were allowed free access to water and were fed on commercial low sodium diets supplemented with 0, 50, 100 or 250 mmol of sodium chloride/day for 6 days. 2. The preprandial plasma sodium concentration was not altered by the dietary sodium intake. However, the 4 h postprandial plasma sodium concentration was linearly related to the magnitude of dietary sodium intake, whereas the 8 h postprandial plasma sodium concentration was elevated only in dogs receiving 250 mmol of sodium/day. 3. The (0–8 h/0–24 h) ratio for urinary sodium excretion was significantly correlated with both the dietary sodium intake and the postprandial increase in plasma sodium concentration. 4. The 24 h excretion of potassium was not markedly affected by the dietary sodium intake; however, the (0–8 h/0–24 h) ratio for potassium excretion was significantly correlated with both the dietary sodium intake and the (0–8 h/0–24 h) ratio for sodium excretion. 5. These data indicate that: (a) postprandial increases in plasma sodium concentration need to be considered when evaluating the mechanisms involved in the daily regulation of sodium balance; (b) the daily pattern of potassium excretion is closely linked to the dietary sodium intake.

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