Comparison of cerebrospinal fluid transport in fetal and adult sheep

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2001-10, Vol.281 (4), p.1215-R1223
• Main Authors: Mollanji, R, Papaiconomou, C, Boulton, M, Midha, R, Johnston, M
• Format: Article
• Language: English
• Subjects: Animals; Biological Transport - physiology; Cerebrospinal Fluid - physiology; Cerebrospinal Fluid Pressure - physiology; Female; Fetus - physiology; Injections, Intraventricular; Intracranial Pressure - physiology; Pregnancy; Serum Albumin, Radio-Iodinated - blood; Serum Albumin, Radio-Iodinated - cerebrospinal fluid; Serum Albumin, Radio-Iodinated - pharmacokinetics; Solutions - administration & dosage; Solutions - pharmacokinetics
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.2001.281.4.R1215

1  Trauma Research Program, Department of Laboratory Medicine and Pathobiology and 2  Division of Neurosurgery, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Toronto, Ontario M4N 3M5, Canada We quantified cerebrospinal fluid (CSF) transport (conductance) and CSF outflow resistance in late-gestation fetal and adult sheep using two methods, a constant pressure infusion method and a bolus injection technique into the lateral ventricles. No significant differences in CSF conductance (fetus 0.013 ± 0.002, adult 0.014   ± 0.003 ml · min 1 · cmH 2 O 1 ) or CSF outflow resistance (fetus 83.7 ± 9.8, adult 84.7 ± 19.7   cmH 2 O · ml 1 · min) were observed. To confirm CSF transport to plasma in fetal animals, 125 I- or 131 I-labeled human serum albumin (HSA) was injected into the lateral ventricles. The tracer entered fetal plasma with an average mass transport rate of 1.91 ± 0.47% injected/h ( n  = 9). In two fetuses, we monitored the tracer appearance in plasma and cervical and thoracic duct lymph after injection of radioactive HSA into the ventricular CSF. As was the case in adult animals, fetal tracer concentrations increased in all three compartments over time, with the highest concentrations measured in lymph collected from the cervical lymphatics. These results 1 ) indicate that global CSF transport parameters in the late-gestation fetus and adult sheep are similar and 2 ) suggest an important role for extracranial lymphatic vessels in CSF transport before birth. arachnoid villi; lymphatic vessels; intracranial pressure; cerebrospinal fluid pressure; fetal cerebrospinal fluid outflow resistance; fetal cerebrospinal fluid conductance; cribriform plate; hydrocephalus