Control of atrial natriuretic factor by right and left atrial distension in
pregnant sheep.
Javeshghani, D., S. Mukaddam-Daher, L. Fan, Z. Guan, J. Gutkowska, B.
Nuwayhid, and E. W. Quillen, Jr.
Department of Obstetrics and Gynecology, McGill University, Montreal,
Centre de Recherche Hotel-Dieu de Montr[acute]eal, Montreal
APStracts 2:0008R, 1995.
Previous studies of the atrial stretch-ANF relationship during pregnancy have
employed volume expansion and measured only right atrial pressure (RAP).
Consequently, we studied nonpregnant (N=7) and 115-125 day pregnant (N=7)
sheep and assessed the ANF response to changes of RAP and 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 bpm) 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
where a 10 mmHg increase in RAP increased ANF by an average of 95+/-9 fmol/ml.
In nonpregnant sheep, the LAP-ANF relationship was more responsive than RAP
-ANF since 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 since 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.
Received 27 December 1993; accepted in final form 9 January 1995.
APS Manuscript Number R701-3.
Article publication pending Am. J. Physiol. (Regulatory Integrative Comp.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.