Effects of the Baroreceptor Reflex System on Atrial Natriuretic Factor Secretion during Volume Expansion in Dogs

1989 ◽  
Vol 77 (1) ◽  
pp. 29-34 ◽  
Author(s):  
K. Kohara ◽  
A. Otsuka ◽  
H. Mikami ◽  
K. Katahira ◽  
T. Tsunetoshi ◽  
...  
Keyword(s):  
Arginine Vasopressin ◽  
Atrial Natriuretic Factor ◽  
Volume Expansion ◽  
Baroreceptor Reflex ◽  
Right Atrial ◽  
Control Group ◽  
Natriuretic Factor ◽  
Plasma Noradrenaline Level ◽  
Reflex System ◽  
Atrial Natriuretic

1. The purpose of this study was to determine whether the baroreceptor reflex system affects the secretion of atrial natriuretic factor directly or indirectly during acute volume expansion. 2. Lactated Ringer's solution containing low mol. wt. dextran was infused at 20 ml/kg for 1 h into dogs in which baroreceptors had been denervated surgically (Vx), dogs in which the autonomic system had been blocked with hexamethonium (Hx) and control dogs. 3. The plasma noradrenaline level was significantly higher in the Vx group and lower in the Hx group than in the control group throughout the experiment. The plasma levels of arginine vasopressin in the Vx and Hx groups were significantly higher than in the control group. 4. The plasma atrial natriuretic factor levels in the three groups showed similar increases during and after volume expansion. 5. The plasma atrial natriuretic factor level was significantly correlated with the right atrial pressure during volume expansion. 6. From these results, it seems unlikely that changes in the plasma level of atrial natriuretic factor during volume expansion are regulated by the baroreceptor reflex directly or indirectly by systemic changes in the sympathetic nervous system or arginine vasopressin secretion.

Plasma vasopressin and atrial natriuretic factor in response to blood volume changes in the anaesthetized rabbit

1989 ◽  
Vol 67 (4) ◽  
pp. 344-352 ◽  
Author(s):  
C. A. Courneya ◽  
N. Wilson ◽  
J. R. Ledsome
Keyword(s):  
Blood Volume ◽  
Atrial Natriuretic Factor ◽  
Volume Expansion ◽  
Vagal Afferents ◽  
Right Atrial ◽  
Volume Changes ◽  
Natriuretic Factor ◽  
Vagal Afferent ◽  
Aortic Baroreceptors ◽  
Atrial Natriuretic

The influence of aortic baroreceptors and vagal afferent nerves on the release of immunoreactive vasopressin (iVP) and immunoreactive atrial natriuretic factor (iANF) was examined in anaesthetized rabbits. Changes in plasma concentrations of iVP and iANF, heart rate, mean arterial pressure, and right atrial pressure were measured in response to blood volume changes (+20, +10, −10, −20%). Carotid sinus pressure was maintained at 100 mmHg (1 mmHg = 133.3 Pa), and blood volume changes were performed before and after bilateral vagotomy (VNX) in all experiments. Two experimental groups were studied: rabbits with aortic depressor nerves intact (ADNI) and those with aortic depressor nerves sectioned (ADNX). Mean arterial and right atrial pressures decreased during haemorrhage and increased in response to volume expansion. Plasma iVP concentrations increased with haemorrhage and decreased with volume expansion in the ADNI group. Plasma iANF, however, decreased with haemorrhage and increased during volume expansion in both ADNI and ADNX groups. Vagotomy caused an increase in baseline plasma iANF in the ADNX group. The responses of iANF to blood volume changes were augmented after VNX and ADNX. The results show that neither the aortic baroreceptor nor the vagal afferent input are needed for the iANF response to changes in blood volume, over the range of ± 20%. In contrast, intact aortic baroreceptors are essential for changes in circulating iVP in this preparation.Key words: vasopressin, atrial natriuretic factor, blood volume, aortic baroreceptors, vagal afferents.

The contribution of atrial natriuretic factor to acute volume natriuresis in rats

1987 ◽  
Vol 253 (6) ◽  
pp. F1129-F1135 ◽  
Author(s):  
R. W. Barbee ◽  
N. C. Trippodo
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Atrial Natriuretic Factor ◽  
Volume Expansion ◽  
Urinary Sodium Excretion ◽  
Right Atrial ◽  
Natriuretic Factor ◽  
Blood Volume Expansion ◽  
Atrial Natriuretic

To explore the role of atrial natriuretic factor (ANF) in acute volume-expansion natriuresis, right atrial pressure (RAP), mean arterial pressure (MAP), rate of urinary sodium excretion (UNaV), and plasma immunoreactive ANF (IR-ANF) were measured in anesthetized, open-chest rats. All groups received 33% blood volume expansion with whole blood in 15 min. RAP was not allowed to increase in one group by using a caval snare. MAP was controlled in a second group with the use of an aortic snare. A third group (RAP-controlled ANF) with control of RAP received rat ANF (99-126) at doses designed to mimic the IR-ANF measured in the MAP-controlled rats. IR-ANF was similar 5 min after blood infusion in rats exhibiting increased RAP (490 +/- 111 pg/ml) and in those without increased RAP but receiving ANF infusion (447 +/- 44 pg/ml); this was also true at 45 min after blood infusion (232 +/- 44 vs. 263 +/- 27 pg/ml). IR-ANF in rats with constant RAP (without ANF infusion) remained low throughout the experiment (61 +/- 10 and 74 +/- 10 pg/ml). UNaV increased only in the MAP-controlled and ANF-infused groups, but peak responses occurred 15-30 min after the onset of volume expansion in the former, and 60-75 min in the latter. Thus, factors other than ANF mostly accounted for the immediate natriuresis after volume expansion, whereas ANF predominated after a delayed period. The results suggest that increased plasma ANF accounted for at least 34% of the observed natriuretic response to acute volume expansion in anesthetized rats.

Relationship between atrial granularity and release of atrial natriuretic factor in rats with diabetes mellitus

1989 ◽  
Vol 257 (4) ◽  
pp. R932-R938 ◽  
Author(s):  
R. A. Hebden ◽  
M. E. Todd ◽  
J. H. McNeill
Keyword(s):  
Atrial Natriuretic Factor ◽  
Volume Expansion ◽  
Pressure Control ◽  
Diabetic Rats ◽  
Right Atrial ◽  
Morphological Examination ◽  
Natriuretic Factor ◽  
Blood Volume Expansion ◽  
Right Atria ◽  
Atrial Natriuretic

We examined the effect of a 25% blood volume expansion on the release of atrial natriuretic factor (ANF) in conscious Wistar rats (13-15 wk old) injected 6 wk earlier with streptozotocin (55 mg/kg iv, diabetic) or saline (1 ml/kg iv, control). The diabetic rats demonstrated a significant (P less than 0.05) resting hypotension (132 +/- 2/91 +/- 1 mmHg, systolic/diastolic) and bradycardia (340 +/- 5 beats/min) compared with the controls (145 +/- 2/98 +/- 2 mmHg, 377 +/- 8 beats/min). Resting plasma immunoreactive (IR) ANF levels were significantly (P less than 0.05) elevated in the diabetic rats (control: 72 +/- 4 pg/ml; diabetic: 87 +/- 4), although resting right atrial pressures were not different (control: 6.0 +/- 0.8 cmH2O; diabetic: 5.2 +/- 0.6). Volume expansion with donor blood from similarly treated animals significantly (P less than 0.05) elevated IR ANF levels in both groups, but the increase in the saline-injected group (+527 +/- 80 pg/ml) was significantly (P less than 0.05) greater than that of the streptozotocin-injected group (+323 +/- 45 pg/ml). Both groups showed similar elevations in right atrial pressure (control: +1.8 +/- 0.3 cmH2O; diabetic: +1.6 +/- 0.4). Morphological examination of tissue taken from right atria demonstrated no difference in cardiocyte volume percent per unit of tissue but a significant (P less than 0.05) reduction in the relative frequency of occurrence of atrial granules in the diabetic group. The cause of the reduction in atrial granularity in these animals is as yet unknown.

Control of atrial natriuretic factor by right and left atrial distension in pregnant sheep

1995 ◽  
Vol 268 (6) ◽  
pp. R1411-R1417
Author(s):  
D. Javeshghani ◽  
S. Mukaddam-Daher ◽  
L. Fan ◽  
Z. Guan ◽  
J. Gutkowska ◽  
...  
Keyword(s):  
Atrial Natriuretic Factor ◽  
Left Atrial ◽  
Atrial Pressure ◽  
Right Atrial ◽  
Natriuretic Factor ◽  
Pregnant Sheep ◽  
Vascular Catheters ◽  
The Right ◽  
Left Atrial Distension ◽  
Atrial Natriuretic

Previous studies of the atrial stretch-atrial natriuretic factor (ANF) relationship during pregnancy have employed volume expansion and measured only right atrial pressure (RAP). Consequently, we studied nonpregnant (n = 7) and 115- to 125-day pregnant (n = 7) sheep and assessed the ANF response to changes of RAP and left atrial pressure (LAP) induced by graded balloon inflation. Ewes prepared with vascular catheters and atrial balloons were studied after recovery from preparatory surgical procedures. The basal levels of mean arterial pressure (MAP, 83 +/- 3 mmHg), RAP (2.1 +/- 0.7 mmHg), LAP (4.7 +/- 0.9 mmHg), and heart rate (HR, 102 +/- 6 beats/min) were similar in nonpregnant and pregnant sheep. Pregnancy also resulted in elevation of ANF concentration from 25 +/- 6 to 57 +/- 4 fmol/ml. With right atrial distension, the RAP-ANF relationships were similar in both nonpregnant and pregnant sheep, with a 10-mmHg increase in RAP increasing ANF by an average of 95 +/- 9 fmol/ml. In nonpregnant sheep, the LAP-ANF relationship was more responsive than RAP-ANF because a 10-mmHg increase in LAP resulted in a 193 +/- 10 fmol/ml increase in ANF. Moreover, during pregnancy, the LAP-ANF relationship was significantly more sensitive because a 10-mmHg increase in LAP resulted in a 433 +/- 15 fmol/ml elevation of ANF. These data demonstrate that plasma ANF levels are more responsive to distension of the left atria than to the right. More importantly, the ANF response to left, but not right, atrial distension is enhanced by pregnancy.

Neural influences on renal responses to acute volume expansion in rats with heart failure

1996 ◽  
Vol 271 (4) ◽  
pp. H1441-H1448 ◽  
Author(s):  
K. P. Patel ◽  
P. L. Zhang ◽  
P. K. Carmines
Keyword(s):  
Heart Failure ◽  
Atrial Natriuretic Factor ◽  
Volume Expansion ◽  
Renal Nerve ◽  
Natriuretic Factor ◽  
Renal Nerve Activity ◽  
Neural Influences ◽  
Renal Responses ◽  
Renal Sympathetic ◽  
Atrial Natriuretic

Experiments were performed to test the postulate that neural influences underlie the suppressed excretory response to acute volume expansion (VE) typically observed 3-4 wk after myocardial infarction to induce chronic heart failure (CHF). Responses to VE were assessed in innervated (intact) and denervated (DNX) kidneys of anesthetized CHF rats and sham-operated controls. CHF rats exhibited blunted natriuretic responses to VE in both intact kidneys (35% of sham response) and DNX kidneys (55% of sham DNX response). CHF rats also displayed suppressed excretory responses to atrial natriuretic factor (0.25 microgram.kg-1.min-1 iv) in both intact kidneys (74% of sham response) and DNX kidneys (63% of sham DNX response). Additional experiments confirmed that the compliance of the venoatrial junction did not differ between sham rats (52 +/- 2 mmHg/microliter) and CHF rats (54-2 mmHg/microliter). The observations support the contention that both tonic renal sympathetic renal nerve activity and suppressed renal atrial natriuretic factor responsiveness likely contribute to the blunted excretory response to VE during CHF.

Effect of blood volume expansion and sympathetic denervation on plasma levels of atrial natriuretic factor (ANF) in the rat

1985 ◽  
Vol 124 (2) ◽  
pp. 309-311 ◽  
Author(s):  
ANDERS PETTERSSON ◽  
SVEN-ERIK RICKSTEN ◽  
ANDREW C. TOWLE ◽  
JAN HEDNER ◽  
THOMAS HEDNER
Keyword(s):  
Blood Volume ◽  
Plasma Levels ◽  
Atrial Natriuretic Factor ◽  
Volume Expansion ◽  
Sympathetic Denervation ◽  
Natriuretic Factor ◽  
Blood Volume Expansion ◽  
Atrial Natriuretic

Atrial dynamics, atrial natriuretic factor, tachycardia, and blood volume in anesthetized rabbits

1991 ◽  
Vol 261 (1) ◽  
pp. H22-H28 ◽  
Author(s):  
K. A. King ◽  
J. R. Ledsome
Keyword(s):  
Blood Volume ◽  
Atrial Natriuretic Factor ◽  
Left Atrial ◽  
Wall Stress ◽  
Atrial Pressure ◽  
Right Atrial ◽  
Right Atrial Pressure ◽  
Atrial Wall ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

The effects of tachycardia and a slow (1%/min) 20% reduction and elevation of blood volume (BV) on right atrial pressure (RAP), right atrial dimension (RAD), and plasma immunoreactive atrial natriuretic factor (IR-ANF) were examined in anesthetized rabbits. Plasma IR-ANF was significantly increased during pacing at 6 Hz in the presence of high BV but not at low BV. Mean RAP increased with expansion of BV, but this change was not associated with significant changes in IR-ANF. There were no statistically significant changes in systolic or diastolic RAD with alterations in BV or with tachycardia. Tachycardia had no effect on left atrial dimension. Diastolic right atrial wall stress (DRAS) and minute DRAS increased with a 20% increase in BV, but changes in BV did not affect systolic right atrial wall stress (SRAS) or minute SRAS. Tachycardia decreased DRAS at high BV and significantly increased SRAS and minute SRAS. The increases in SRAS and minute SRAS were greater during tachycardia at high BV, suggesting that an interaction between BV and tachycardia results in potentiation of SRAS and minute SRAS. The results suggest that systolic RAS is a significant factor in ANF release during tachycardia at high BV.

Right atrial appendectomy reduces the renal response to acute hypervolemia in the rat

1984 ◽  
Vol 247 (3) ◽  
pp. R610-R613 ◽  
Author(s):  
A. T. Veress ◽  
H. Sonnenberg
Keyword(s):  
Atrial Natriuretic Factor ◽  
Control Period ◽  
Atrial Appendage ◽  
Right Atrial ◽  
Blood Flows ◽  
Natriuretic Factor ◽  
Right Atrial Appendage ◽  
The Right ◽  
Experimental Group ◽  
Atrial Natriuretic

We have shown previously that an extract of atrial tissue from rat heart contains a potent natriuretic factor. In this study anesthetized rats were connected to a respirator and the right atrial appendage was either excised, using a loop ligature (experimental group), or the loop was placed around the appendage and then removed (sham-operated group). After equilibration and control urine collection periods an isooncotic Ringers-albumin solution was infused intravenously (25% of estimated blood volume), and renal function was monitored over the next hour. There were no differences between groups in control period arterial or central venous pressures, heart rates, cardiac outputs, renal blood flows, or filtration rates. However, the diuretic and natriuretic responses to infusion in the experimental group were only one half of those in the sham-operated series (vol = 23.4 +/- 6.2 vs. 68.2 +/- 11.0 microliter X min-1 X g kidney wt-1, UNa V = 2,731 +/- 856 vs. 6,504 +/- 962 nmol X min-1 X g kidney wt-1). These differences were not affected by prior bilateral vagotomy. Administration of homologous atrial natriuretic factor or furosemide resulted in identical renal responses in both groups. We conclude therefore that acute hypervolemia is associated with release of atrial natriuretic factor into the bloodstream and that removal of the atrial appendage reduces the amount available for such release.

Atrial Natriuretic Factor in Central Cardiovascular Control

Physiology ◽  
1993 ◽  
Vol 8 (5) ◽  
pp. 223-228 ◽  
Author(s):  
S Oparil ◽  
JM Wyss
Keyword(s):  
Atrial Natriuretic Factor ◽  
Spontaneously Hypertensive Rat ◽  
Brain Regions ◽  
Baroreceptor Reflex ◽  
Hypothalamic Area ◽  
Spontaneously Hypertensive ◽  
Natriuretic Factor ◽  
Effector System ◽  
Baroreceptor Reflex Sensitivity ◽  
Atrial Natriuretic

A complete atrial natriuretic factor (ANF) synthetic, processing, and effector system is found in rat brain. ANF in critical brain regions, including anterior hypothalamic area and nucleus tractus solitarii, contributes importantly to the tonic control of blood pressure, sympathetic outflow, and baroreceptor reflex sensitivity in the spontaneously hypertensive rat.

Interaction of atrial natriuretic factor and angiotensin II in proximal HCO3- reabsorption

1992 ◽  
Vol 262 (2) ◽  
pp. F303-F308 ◽  
Author(s):  
G. N. Gomes ◽  
M. M. Aires
Keyword(s):  
Angiotensin Ii ◽  
Atrial Natriuretic Factor ◽  
Control Group ◽  
Ang Ii ◽  
Half Time ◽  
Capillary Perfusion ◽  
Perfusion Fluid ◽  
Natriuretic Factor ◽  
Peritubular Capillaries ◽  
Atrial Natriuretic

Bicarbonate reabsorption was evaluated by the acidification kinetics technique in middle proximal tubule in Munich-Wistar rats. Atrial natriuretic factor (ANF) and angiotensin II (ANG II) were infused into the jugular vein (ANF, 0.5 microgram.min-1.kg-1 after a prime of 10 micrograms/kg; ANG II, 20 ng.min-1.kg-1) or added to luminal or peritubular perfusion fluid (10(-6) M ANF; 10(-12) M ANG II). In the presence of ANF, in each condition, no significant differences in net HCO3- reabsorption or in acidification half time were observed compared with the control group. In the presence of ANG II, a significant increase in HCO3- reabsorption was observed, expressed by a fall in acidification half time from a mean of 4.75 +/- 0.20 (n = 86) to 2.47 +/- 0.18 s (n = 32) in systemically infused rats or to 2.30 +/- 0.15 s (n = 35) in luminally perfused tubules and from 4.57 +/- 0.32 (n = 44) to 2.04 +/- 0.10 s (n = 50) during capillary perfusion. However, when ANG II was systemically infused or perfused in lumen or in peritubular capillaries, addition of ANF to lumen or capillaries by perfusion or systemic infusion abolished the effects observed with ANG II alone. These studies confirm that ANG II stimulates proximal HCO3- reabsorption and show that ANF alone does not affect this process, but impairs the stimulation caused by ANG II.

Sign in / Sign up

Export Citation Format

Share Document