Hemodynamic and hormonal responses to atrial distension in the ovine fetus.
OBJECTIVE
Our purpose was to evaluate the hemodynamic and endocrine responses to elevations of atrial pressure in fetal sheep.


METHODS
By use of a randomized block design, 10 ovine fetuses underwent pulmonary artery constriction proximal to the ductus arteriosus with and without propranolol pretreatment.


RESULTS
Atrial pressure doubled (p < 0.05), whereas mean arterial pressure remained unchanged (p > 0.05), in response to pulmonary artery constriction in both groups. Atrial natriuretic peptide tripled (p < 0.01), arginine vasopressin tripled (p < 0.05), and plasma renin activity doubled (p < 0.05) in both the constriction and constriction plus propranolol groups. No changes in fetal hematocrit values were demonstrated in any group.


CONCLUSIONS
The fetal sheep responds to increased atrial pressure with not only increased levels of atrial natriuretic peptide but also with arginine vasopressin and plasma renin activity over time. These changes occur in spite of increases in both atrial pressure and atrial natriuretic peptide. We speculate that the fetal heart may participate in redistribution of cardiac output by releasing atrial natriuretic peptide and augmenting secretion of arginine vasopressin and plasma renin activity.
Jaekle
R K
RK
Department of Obstetrics and Gynecology, Wake Forest University Medical Center, Winston-Salem, North Carolina, USA.
Sheikh
A U
AU
Berry
D D
DD
Washburn
L
L
Rose
J C
JC
D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood*; D016275:Atrial Function / Q000502:physiology; D009320:Atrial Natriuretic Factor / Q000097:blood*; D001794:Blood Pressure; D003250:Constriction; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005318:Fetal Heart / Q000502:physiology*; D006325:Heart Atria / Q000196:embryology; D006439:Hemodynamics; D007700:Kinetics; D011247:Pregnancy; D011312:Pressure; D011433:Propranolol / Q000494:pharmacology; D011651:Pulmonary Artery / Q000196:embryology / Q000502:physiology; D012083:Renin / Q000097:blood*; D012756:Sheep
D001127:Arginine Vasopressin; D009320:Atrial Natriuretic Factor; D011433:Propranolol; D012083:Renin