901-29 Effects of Positive EndExpiratory Pressure Ventilation on Right Atrial Size and Atrial Natriuretic Factor Release in Humans

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.

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Changes in atrial specific granules and atrial natriuretic factor release in experimental congestive cardiac failure

Journal of Molecular and Cellular Cardiology ◽

10.1016/0022-2828(89)91422-3 ◽

1989 ◽

Vol 21 ◽

pp. S70

Author(s):

G AGNOLETTI

Keyword(s):

Cardiac Failure ◽

Atrial Natriuretic Factor ◽

Congestive Cardiac Failure ◽

Natriuretic Factor ◽

Specific Granules ◽

Atrial Specific Granules ◽

Factor Release ◽

Atrial Natriuretic

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

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1991.261.1.h22 ◽

1991 ◽

Vol 261 (1) ◽

pp. H22-H28 ◽

Cited By ~ 1

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.

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

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1984.247.3.r610 ◽

1984 ◽

Vol 247 (3) ◽

pp. R610-R613 ◽

Cited By ~ 2

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.

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