AJP - Endocrinology and Metabolism, Vol 249, Issue 3 287-E291, Copyright © 1985 by American Physiological Society
Amniotic fluid ionic concentration in response to chronic fetal vasopressin infusion
M. G. Ross, M. G. Ervin, R. D. Leake and D. A. Fisher
Chronically prepared, third trimester fetal lambs were administered 72-h
intravenous infusions of arginine vasopressin (AVP) (65 or 130 mU/kg h) or
0.9% saline. Saline infusion preceding the AVP infusion did not change
amniotic fluid (AF) composition. During the AVP infusion, there were
significant increases in amniotic fluid osmolality (278.8 +/- 4.9 to 302.1
+/- 4.5 mosm) and in sodium (122.7 +/- 3.3 to 135.3 +/- 3.6 meq/l) and
potassium (9.7 +/- 2.6 to 13.8 +/- 1.3 meq/l) concentrations. Saline
infusion after the AVP infusion resulted in return of AF osmolality,
sodium, and potassium toward normal levels. Fetal plasma and amniotic fluid
AVP levels measured by radioimmunoassay significantly increased during AVP
infusion and decreased during the subsequent saline infusion. There were no
changes in maternal or fetal plasma osmolality in response to AVP. These
results suggest that fetal AVP released in response to intrauterine stress
may alter the composition and osmolality of amniotic fluid in a reversible
manner.
