Atrial peptide potentiates renal responses to volume expansion in conscious dogs

1989 ◽  
Vol 256 (1) ◽  
pp. R284-R289
Author(s):  
C. H. Metzler ◽  
D. J. Ramsay
Keyword(s):  
Sodium Excretion ◽  
Urine Volume ◽  
Extracellular Fluid ◽  
Urinary Sodium Excretion ◽  
Urine Flow ◽  
Conscious Dogs ◽  
Physiological Dose ◽  
Peptide Secretion ◽  
Renal Responses ◽  
Dose Dependent

Experiments were performed to compare the renal responses to atrial peptide infusion in conscious dogs with normal and expanded extracellular fluid volumes to test the hypothesis that the renal responses to atrial peptide infusions are dependent on the prevailing fluid and electrolyte status in the animal. Atrial peptide-(99-126) was infused intravenously in doses of either 0, 5, 25, or 100 ng.kg-1.min-1 in conscious dogs prepared with chronic catheters in the femoral artery and vein and the urinary bladder. In dogs with normal extracellular fluid volume, atrial peptide caused small increases in urinary sodium excretion with the high physiological (25 ng.kg-1.min-1) and pharmacological (100 ng.kg-1.min-1) doses. Urine volume and potassium excretion were increased only at the highest pharmacological dose. In contrast, atrial peptide infusion in dogs that were volume expanded by infusion of hypertonic saline showed dramatic, dose-dependent increases in sodium excretion and urine flow with all doses tested. The low, physiological dose of atrial peptide (5 ng.kg-1.min-1) increased sodium excretion and urine flow rate in volume-expanded dogs more than the pharmacological dose in normal dogs (n = 4). These results demonstrate that the renal responses to atrial peptide infusion are potentiated in dogs that are volume expanded and suggest that under conditions where atrial peptide secretion would be enhanced, small changes in plasma atrial peptide concentration can have significant effects on renal function.

Role of renal arterial pressure in the regulation of extracellular volume in conscious dogs

1992 ◽  
Vol 82 (3) ◽  
pp. 247-254 ◽  
Author(s):  
Gabriele Kaczmarczyk ◽  
Klaus Schröder ◽  
Dirk Lampe ◽  
Rainer Mohnhaupt
Keyword(s):  
Body Weight ◽  
Arterial Pressure ◽  
Sodium Excretion ◽  
Urine Volume ◽  
Extracellular Fluid ◽  
Fluid Volume ◽  
Extracellular Fluid Volume ◽  
Conscious Dogs ◽  
Central Venous ◽  
Infusion Period

1. This study in conscious dogs examined the quantitative effects of a reduction in the renal arterial pressure on the renal homoeostatic responses to an acute extracellular fluid volume expansion. 2. Seven female beagle dogs were chronically instrumented with two aortic catheters, one central venous catheter and a suprarenal aortic cuff, and were kept under standardized conditions on a constant high dietary sodium intake (14.5 mmol of Na+ day−1 kg−1 body weight). 3. After a 60 min control period, 0.9% (w/v) NaCl was infused at a rate of 1 ml min−1 kg−1 body weight for 60 min (infusion period). Two different protocols were applied during the infusion period: renal arterial pressure was maintained at 102 ± 1 mmHg by means of a servo-feedback control circuit (RAP-sc, 14 experiments) or was left free (RAP-f, 14 experiments). 4. During the infusion period, in the RAP-sc protocol as well as in the RAP-f protocol, the mean arterial pressure increased by 10 mmHg, the heart rate increased by 20 beats/min, the central venous pressure increased by 4 cmH2O and the glomerular filtration rate (control 5.1 ± 0.3 ml min−1 kg−1 body weight, mean ± sem) increased by 1 ml min−1 kg−1. 5. Plasma renin activity [control 0.85 ± 0.15 (RAP-f) and 1.08 ± 0.23 (RAP-sc) pmol of angiotensin I h−1 ml−1] decreased similarly in both protocols. 6. Renal sodium excretion, fractional sodium excretion and urine volume increased more in the RAP-f experiments than in the RAP-sc experiments (P<0.05), renal sodium excretion from 8.2 to 70.1 (RAP-f) and from 7.7 to 47.4 (RAP-sc) μmol min−1 kg−1 body weight, fractional sodium excretion from 1.1 to 8.0 (RAP-f) and from 1.0 to 5.4 (RAP-sc)% and urine volume from 39 to 586 (RAP-f) and from 38 to 471 (RAP-sc) μl min−1 kg−1 body weight. 7. In the RAP-f experiments as well as in the RAP-sc experiments, urinary sodium excretion increased with expansion of the extracellular fluid volume, which increased by a maximum of 21% (fasting extracellular fluid volume: 206 ± 4 ml/kg body weight, six dogs, 28 days). 8. The increase in renal arterial pressure contributed significantly to the renal homoeostatic response, as 21% less urine and 31% less sodium were excreted when the extracellular fluid volume was expanded and the renal arterial pressure was kept constant below control pressure rather than being allowed to rise. The differences in sodium and water excretion were mainly due to the effect of renal arterial pressure on tubular reabsorption. However, the striking increase in sodium and urine excretion which occurred despite the reduction in renal arterial pressure emphasizes the importance of other homoeostatic factors involved in body fluid regulation.

Hemodynamic and renal responses to volume expansion in dogs with cardiac denervation

1988 ◽  
Vol 254 (6) ◽  
pp. F780-F786
Author(s):  
R. Pichet ◽  
J. Gutkowska ◽  
M. Cantin ◽  
M. Lavallee
Keyword(s):  
Plasma Levels ◽  
Sodium Excretion ◽  
Atrial Natriuretic Factor ◽  
Volume Expansion ◽  
Urine Flow ◽  
Conscious Dogs ◽  
Base Line ◽  
Aortic Constriction ◽  
Cardiac Denervation ◽  
Renal Responses

Hemodynamic responses, renal function, and plasma levels of immunoreactive atrial natriuretic factor (irANF) were examined following volume expansion (VE) in normal (N) conscious dogs and in conscious dogs with cardiac denervation (CD). Base-line urine flow was consistently greater (P less than 0.05) in dogs with CD (0.54 +/- 0.06 ml/min) than in N (0.29 +/- 0.03 ml/min) dogs but sodium excretion did not differ between N (2.80 +/- 0.58 mu eq.min-1.kg body wt-1) and CD (3.53 +/- 0.75 mu eq.min-1.kg-1) groups. With VE (18 ml/kg of 3% dextran in saline), mean arterial pressure (MAP) increased (P less than 0.01) by 16 +/- 3 from 103 +/- 4 mmHg in N dogs but did not change from pre-VE base line (103 +/- 2 mmHg) in dogs with CD. At 10 min after VE, urine flow increased more (P less than 0.01) in N dogs (1.39 +/- 0.24 ml/min) than in dogs with CD (0.26 +/- 0.09 ml/min). At that time, increases in sodium excretion were also greater (P less than 0.01) in N (9.13 +/- 1.96 mu eq.min-1.kg-1) dogs than in dogs with CD (1.06 +/- 0.68 mu eq.min-1.kg-1). With VE, increases in irANF plasma levels were not different in N dogs (40 +/- 12 from 34 +/- 5 pg/ml) and in dogs with CD (27 +/- 3 from 45 +/- 7 pg/ml). In dogs with CD, when MAP was increased by aortic constriction to mimic responses observed in N dogs, renal responses were similar to those of N dogs.(ABSTRACT TRUNCATEDAT 250 WORDS)

Fasting induces denervation natriuresis in the conscious rat

1985 ◽  
Vol 249 (5) ◽  
pp. F753-F758 ◽  
Author(s):  
G. Szenasi ◽  
P. Bencsath ◽  
L. Szalay ◽  
L. Takacs
Keyword(s):  
Sodium Excretion ◽  
Left Kidney ◽  
Extracellular Fluid ◽  
Urinary Sodium Excretion ◽  
Urine Flow ◽  
Urinary Sodium ◽  
Renal Nerves ◽  
Sham Operation ◽  
Conscious Rats ◽  
Fasted Rats

The participation of renal nerves in the regulation of sodium excretion was studied in fed and overnight-fasted rats subjected to acute or chronic left kidney denervation or sham operation. Clearance experiments were performed on conscious restrained animals. Urine flow, glomerular filtration rate (GFR), and urinary sodium excretion were not different in left and right kidneys of sham-operated rats. In fed conscious rats, urine flow, GFR, and urinary sodium excretion of innervated (I) and denervated (D) kidneys were similar. In fasted conscious rats, significant denervation natriuresis was observed after both acute (I, 1.06 +/- 0.27; D, 1.56 +/- 0.40 mumol . min-1 . g-1, P less than 0.05) and chronic (I, 1.55 +/- 0.19; D, 2.20 +/- 0.18 mumol . min-1 . g-1, P less than 0.01) renal sympathectomy, whereas urine flow and GFR in I and D kidneys were not different. Additional experiments revealed that extracellular fluid and plasma volumes of fasted rats were decreased by approximately 10% compared with those of fed animals due to a significant overnight natriuresis and negative water balance. In fed conscious rats, the renal nerves do not seem to participate in the regulation of sodium excretion. The presence of denervation natriuresis in conscious fasted rats suggests that renal nerves are involved in sodium conservation during fasting to maintain extracellular fluid and plasma volume.

Renal responses to oxytocin during the 4 days of the oestrous cycle in the rat

1997 ◽  
Vol 154 (2) ◽  
pp. 347-353 ◽  
Author(s):  
R J Windle ◽  
M L Forsling
Keyword(s):  
Sodium Excretion ◽  
Dose Range ◽  
Virgin Female ◽  
Urine Flow ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Female Rat ◽  
Oxytocin Infusion ◽  
Renal Responses ◽  
Dose Dependent

Abstract Oxytocin was administered to virgin female rats at doses of 25–200 pmol/min during 0·077 mol NaCl/l infusion at 150 μl/min on each day of the oestrous cycle. The resultant rates of urine flow, glomerular filtration (GFR) and electrolyte excretion were determined. Oxytocin caused significant increases in urine flow (P<0·001) and sodium excretion (P<0·001); both responses being dose-dependent (P<0·02 and P<0·01 respectively). Significant variations in the renal responsiveness to the hormone occurred over the 4 days of the oestrous cycle. On oestrus the lowest dose of 25 pmol oxytocin/min produced a significant increase in urine flow (from 139·5 ± 4·3 to 165·6 ± 7·1 μl/min, P<0·005) and a dose of 50 pmol/min produced a significant increase in sodium excretion (from 10·6 ± 0·1 to 14·5 ± 0·7 μmol/min, P<0·005). Significant increases in urine flow and sodium excretion were seen on pro-oestrus with hormone administration rates of 50 and 100 pmol/min respectively and on dioestrus day 2 with a rate of 100 pmol/min. On dioestrus day 1 no increase in urine flow or sodium excretion was seen over the dose range of oxytocin administration. A dose of 100 pmol oxytocin/min significantly increased GFR on pro-oestrus and dioestrus day 2, but not on the other 2 days of the cycle. The circulating hormone concentrations produced by oxytocin infusion were similar on each day of the cycle and so could not account for the differences seen. Therefore, these results suggest varying renal responsiveness to oxytocin during the reproductive cycle of the female rat. Journal of Endocrinology (1997) 154, 347–353

Effects of left atrial stretch in cardiac-denervated and intact conscious dogs

1982 ◽  
Vol 242 (6) ◽  
pp. H1056-H1064 ◽  
Author(s):  
D. C. Fater ◽  
H. D. Schultz ◽  
W. D. Sundet ◽  
J. S. Mapes ◽  
K. L. Goetz
Keyword(s):  
Heart Rate ◽  
Renal Function ◽  
Left Atrium ◽  
Blood Volume ◽  
Sodium Excretion ◽  
Left Atrial ◽  
Urine Flow ◽  
Conscious Dogs ◽  
Circulating Blood Volume ◽  
Renal Responses

We monitored cardiovascular and renal function in conscious dogs with surgically denervated hearts during two experimental procedures: 1) inflation of a balloon in the left atrium and 2) intravascular volume expansion. The results obtained were compared with results from identical experiments on sham-operated control dogs. Left atrial balloon inflation in the sham-operated dogs produced an increase in left atrial pressure, heart rate, urine flow, and sodium excretion; central venous pressure decreased. These changes were absent in the cardiac-denervated dogs. Infusion of 6% dextran in isotonic saline (16% of estimated blood volume) increased the heart rate significantly in the control dogs but not in the cardiac-denervated dogs; other hemodynamic measurements were comparable in the two groups. Urine flow and sodium excretion increased significantly in both the cardiac-denervated and control dogs; the responses did not differ significantly between the two groups. These experiments demonstrate that inflation of a balloon in the left atrium of a conscious dog elicits diuretic and natriuretic responses that are dependent on intact cardiac neural pathways, presumably specifically dependent on afferent neural impulses from left atrial receptors. On the other hand, an increase in circulating blood volume induced by the intravenous infusion of an isotonic, isoncotic solution elicits diuretic and natriuretic responses in the cardiac-denervated dog that are similar to the renal responses produced in a control dog. Thus, although cardiac receptors are capable of eliciting reflex changes in both hemodynamics and renal function, it is not clear what role they play in mediating the renal responses evoked by increases in blood volume.

Control of atrial natriuretic factor release in conscious dogs

1986 ◽  
Vol 251 (5) ◽  
pp. R947-R956 ◽  
Author(s):  
K. M. Verburg ◽  
R. H. Freeman ◽  
J. O. Davis ◽  
D. Villarreal ◽  
R. C. Vari
Keyword(s):  
Sodium Excretion ◽  
Atrial Natriuretic Factor ◽  
Isotonic Saline ◽  
Extracellular Fluid ◽  
Fluid Volume ◽  
Extracellular Fluid Volume ◽  
Conscious Dogs ◽  
Base Line ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

The aim of this study was to examine the changes in the concentration of plasma immunoreactive atrial natriuretic factor (iANF) that occur in response to expansion or depletion of the extracellular fluid volume in conscious dogs. The plasma iANF concentration was also measured postprandially after the ingestion of a meal containing 125 meq of sodium. Postprandial plasma iANF increased 45% (P less than 0.05) above the base-line concentration, and this increase was accompanied by a brisk natriuresis. After a low-sodium meal, however, plasma iANF and sodium excretion failed to increase. The plasma iANF concentration increased from 57 +/- 5 to 139 +/- 36 pg/ml (P less than 0.05) immediately after volume expansion with intravenous isotonic saline infusion (2.5% body wt) administered over a 30-min period; plasma iANF remained elevated at 90 +/- 14 pg/ml (P less than 0.05) for an additional 30 min before returning toward preinfusion levels. Plasma iANF decreased 45% from 78 +/- 17 to 43 +/- 7 pg/ml (P less than 0.05) in response to the administration of ethacrynic acid (2.0 mg/kg, iv bolus) that produced an estimated 15% depletion of intravascular volume. In additional experiments the infusion of synthetic alpha-human ANF at 100 and 300 ng X kg-1 X min-1 increased (P less than 0.05) both the plasma iANF concentration and the urinary excretion of iANF. This study demonstrates that the secretion of ANF is consistently influenced by changes in the extracellular fluid volume. Furthermore, the results support the concept that ANF functions to increase postprandial sodium excretion following the ingestion of a high-sodium meal.

A rapid bioassay for quantification of atrial natriuretic polypeptides

1987 ◽  
Vol 252 (5) ◽  
pp. R1009-R1014 ◽  
Author(s):  
K. Matsui ◽  
T. Kimura ◽  
K. Ota ◽  
M. Shoji ◽  
M. Inoue ◽  
...  
Keyword(s):  
Sodium Excretion ◽  
Urine Volume ◽  
Good Tool ◽  
Spontaneously Hypertensive ◽  
Assay Procedure ◽  
Rapid Bioassay ◽  
Wistar Kyoto ◽  
Dose Dependent ◽  
Atrial Natriuretic

A quantitative bioassay for the detection and quantification of atrial natriuretic polypeptides (ANPs) was developed in a pentobarbital-anesthetized rat. Ten percent mannitol in 0.9% saline was infused to achieve stable diuresis. The conductivity of the urine, urine flow, and blood pressure were continuously recorded. A bolus injection of synthetic alpha-human atrial natriuretic polypeptide (alpha-hANP) elicited dose-dependent increases in the urine conductivity, sodium excretion, and urine volume. Changes in the urine conductivity correlated significantly with the increase in sodium excretion. By use of changes in urine conductivity, biological ANP activity of crude rat atrial extract was determined. Atrial contents of ANP in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) were 25.5 +/- 1.2 microgram per atrium (n = 4) and 25.1 +/- 0.8 (n = 5) in euhydration. They were increased to 27.0 +/- 1.1 micrograms (n = 4) and 29.3 +/- 1.3 (n = 5, P less than 0.05), after 5-day water deprivation, respectively. This assay procedure provides a good tool for rapid and quantitative determination of ANPs.

Interstitial dynamics in rats with early stage experimental cirrhosis of the liver

1989 ◽  
Vol 256 (3) ◽  
pp. F497-F503
Author(s):  
E. Sanz ◽  
C. Caramelo ◽  
J. M. Lopez-Novoa
Keyword(s):  
Sodium Excretion ◽  
Interstitial Fluid ◽  
Early Stage ◽  
Fluid Pressure ◽  
Extracellular Fluid ◽  
Ringer Solution ◽  
Urine Flow ◽  
Cirrhosis Of The Liver ◽  
Experimental Cirrhosis ◽  
Albumin Infusion

Pathogenesis of edema in cirrhosis of the liver is still incompletely understood. The present study was designed to examine interstitial fluid dynamics in cirrhotic, non-ascitic rats, measuring interstitial fluid pressure by means of a subcutaneous plastic capsule in basal conditions during extracellular fluid volume expansion with Ringer solution and during albumin infusion. Urine flow and sodium excretion and plasma and interstitial fluid volumes were simultaneously measured. Cirrhotic rats exhibited reduced urine flow and sodium excretion, both in basal conditions and in response to expansion maneuvers. Plasma and interstitial fluid volumes were higher in cirrhotic than in control animals. Remarkable alterations were present in capsular pressures in cirrhotic rats. In the control rats, basal capsular pressure values were negative, and they increased after Ringer infusion and markedly decreased with albumin infusion. In contrast, in cirrhotic rats, basal capsular pressures were in the positive range and they remained nearly constant during ringer infusion and albumin administration. These results suggest that in cirrhotic rats there are significant alterations in systemic interstitial dynamics, even before ascites formation. Altered systemic capillary dynamics may therefore be important early changes that precede and thus contribute to the formation of edema in cirrhosis.

Rhythmicity of urinary sodium excretion, mean arterial blood pressure, and heart rate in conscious dogs

1992 ◽  
Vol 262 (1) ◽  
pp. H149-H156 ◽  
Author(s):  
U. Palm ◽  
W. Boemke ◽  
H. W. Reinhardt
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Sodium Excretion ◽  
Urinary Sodium Excretion ◽  
Urinary Sodium ◽  
Conscious Dogs ◽  
Arterial Blood ◽  
Infusion Regimen

The existence of urinary excretion rhythms in dogs, which is a matter of controversy, was investigated under strictly controlled intake and environmental conditions. In seven conscious dogs, 14.5 mmol Na, 3.55 mmol K, and 91 ml H2O.kg body wt-1.24 h-1 were either administered with food at 8:30 A.M. or were continuously infused at 2 consecutive days. During these 3 days, automatized 20-min urine collections, mean arterial blood pressure (MABP), and heart rate (HR) recordings were performed without disturbing the dogs. Fundamental and partial periodicities, the noise component of urinary sodium excretion (UNaV), MABP, and HR were analyzed using a method derived from Fourier and Cosinor analysis. Oral intake (OI) leads to powerful 24-h periodicities in all dogs and seems to synchronize UNaV. UNaV on OI peaked between 1 and 3 P.M. Under the infusion regimen, signs of nonstationary rhythms and desynchronization predominated. UNaV under the infusion regimen could be separated into two components: a rather constant component continuously excreted and superimposed to this an oscillating component. No direct coupling between UNaV and MABP periodicities could be demonstrated. On OI, an increase in HR seems to advance the peak UNaV in the postprandial period. HR and MABP signals were both superimposed with noise. We conclude that UNaV rhythms are present in dogs. They are considerably more pronounced on OI.

Preoptic-hypothalamic periventricular lesions reduce natriuresis to volume expansion

1983 ◽  
Vol 244 (1) ◽  
pp. R51-R57 ◽  
Author(s):  
S. L. Bealer ◽  
J. R. Haywood ◽  
K. A. Gruber ◽  
V. M. Buckalew ◽  
G. D. Fink ◽  
...  
Keyword(s):  
Volume Expansion ◽  
Third Ventricle ◽  
Urine Volume ◽  
Extracellular Fluid ◽  
Urinary Sodium Excretion ◽  
Toad Bladder ◽  
Arterial Blood ◽  
Electrolytic Ablation ◽  
High Level ◽  
Periventricular Lesions

The present experiment was designed to determine if electrolytic ablation of the periventricular tissue surrounding the anteroventral third ventricle (AV3V) altered the natriuresis typically seen during isotonic volume expansion. Control and AV3V-lesioned rats received intravenous infusions of 0.9% NaCl at 0.5 ml/min until 10% body weight was given. Arterial blood pressure was monitored, and urine was collected throughout the experiment. Following expansion, blood was processed for analysis of natriuretic hormonelike activity by chromatographic separation of plasma extracts followed by measuring antinatriferic activity across the isolated toad bladder. Urinary sodium excretion and urine volume during expansion were significantly less in rats with lesions surrounding the AV3V region than in control rats. Toad bladder bioassay showed a high level of natriuretic hormonelike activity in control animals following volume expansion, but no natriuretic hormonelike activity in plasma from volume-expanded rats with AV3V lesions. These data demonstrate that AV3V periventricular ablation attenuates the natriuresis induced by isotonic-volume expansion. In addition, preliminary results indicate the AV3V region may be a central site critical for natriuretic hormonelike activity and control of extracellular fluid volume.

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