HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 289/1/H146    most recent 01284.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Faber, J. Articles by Davis, L. Search for Related Content PubMed PubMed Citation Articles by Faber, J. Articles by Davis, L.

Function curve of the membranes that regulate amniotic fluid volume in sheep

¹Department of Physiology and Pharmacology, ²Department of Obstetrics and Gynecology, ³Heart Research Laboratory and ⁴Surgery, School of Medicine, Oregon Health and Sciences University, Portland, Oregon

Submitted 20 December 2004 ; accepted in final form 25 February 2005

Seven singleton 120-day fetal lambs were prepared with a shunt from the lung to the gastric end of the esophagus, a bladder catheter, and multiple amniotic fluid and vascular catheters. The urachus was ligated. Beginning 7 days later, amniotic fluid volumes were determined by drainage, followed by replacement with 1 liter of lactated Ringer (LR) solution. Urine flow into the amnion was measured continuously. In 14 of 27 experiments, amniotic fluid volumes were determined again 2 days after the inflow into the amnion had consisted of urine only and in 13 experiments after the inflow of urine had been supplemented by an intraamniotic infusion of LR solution. Intramembranous absorption was calculated from the inflows and the changes in volume between the beginning and end of each experiment. The relations between absorption rate and amniotic fluid volume, the "function curves," were highly individual. Urine production during the infusion of LR solution did not decrease, fetal plasma renin activity decreased (P < 0.001), and amniotic fluid volume increased by 140% [SE (27%), P < 0.005], but the increase in the amniochorionic absorption rate of 411% [SE (48%), P < 0.001] was greater (P < 0.005) than the increase in volume. Each of the seven fetuses was proven capable of an average intramembranous absorption rate that exceeded 4.5 liters of amniotic fluid per day. During the infusion of LR solution, the increase in the rate of absorption matched the rate of infusion (both in ml/h), with a regression coefficient of 0.75 (P < 0.001). Thus, even for large amniotic fluid volumes, volume is not limited by the absorptive capacity of the amniochorion, and, at least in these preparations, the position of the function curve and not the natural rate of inflow was the major determinant of resting amniotic fluid volume.

fetus; polyhydramnios; amniochorion; intramembranous absorption

This article has been cited by other articles:

				C. Y. Cheung and R. A. Brace Unidirectional Transport Across Cultured Ovine Amniotic Epithelial Cell Monolayer Reproductive Sciences, December 1, 2008; 15(10): 1054 - 1058. [Abstract] [PDF]