Experiments will be performed on fetal sheep of known gestational ages. Indwelling fetal catheters, flow sensors and amniotic and allantoic fluid catheters will be placed during sterile surgeries under general anesthesia. Hypotheses to be tested include: (l) Urine production, although variable, detracts from, rather than contributes to the control of amniotic fluid volume. (2) Neither lung fluid production, nor drinking of amniotic fluid are necessary for an adequate homeostatic response to abnormal production of amniotic fluid. (3) Fetal swallowing may contribute to amniotic fluid volume regulation even if not necessary in sheep. (4) Reabsorption of amniotic fluid is largely insensitive to electrolyte load. (5) Neither the crystalloid osmotic gradient nor the oncotic gradient between amniotic fluid and fetal plasma are involved in volume regulation. (6) The quantity that is being regulated is amniotic fluid volume, rather than intrauterine volume. (7) The absorptive mechanism permits passage of large quantities of macromolecules, such as plasma albumin, even in the absence of drinking.
| Jonker, S S; Anderson, D F; Davis, L E et al. (2008) Persistent changes in arterial blood gases in fetal sheep. Lab Anim 42:326-30 |
| Brace, Robert A; Cheung, Cecilia Y; Davis, Lowell E et al. (2006) Sources of amniotic fluid erythropoietin during normoxia and hypoxia in fetal sheep. Am J Obstet Gynecol 195:246-54 |
| Giraud, George D; Faber, J Job; Jonker, Sonnet S et al. (2006) Effects of intravascular infusions of plasma on placental and systemic blood flow in fetal sheep. Am J Physiol Heart Circ Physiol 291:H2884-8 |
| Faber, J J; Anderson, D F; Jonker, S S et al. (2006) Fetal infusions of plasma cause an increase in umbilical vascular resistance in sheep. Placenta 27:876-81 |
| Anderson, D; Yang, Q; Hohimer, A et al. (2005) Intramembranous absorption rate is unaffected by changes in amniotic fluid composition. Am J Physiol Renal Physiol 288:F964-8 |
| Faber, Job; Anderson, Debra; Hohimer, Roger et al. (2005) Function curve of the membranes that regulate amniotic fluid volume in sheep. Am J Physiol Heart Circ Physiol 289:H146-50 |
| Giraud, George D; Faber, J Job; Jonker, Sonnet et al. (2005) Intravascular infusions of plasma into fetal sheep cause arterial and venous hypertension. J Appl Physiol 99:884-9 |
| Yang, Qin; Davis, L; Hohimer, A et al. (2005) Regulatory response to washout of amniotic fluid in sheep. Am J Physiol Heart Circ Physiol 288:H1339-43 |
| Faber, J Job; Anderson, Debra F (2002) Absorption of amniotic fluid by amniochorion in sheep. Am J Physiol Heart Circ Physiol 282:H850-4 |
