Positive-pressure ventilation alters blood-to-brain and blood-to-CSF transport in neonatal pigs.
These experiments examine the transfer of sucrose, urea, sodium, and albumin from blood to brain in new-born pigs exposed to an increase in ventilation pressure. We also studied the movement of urea and sodium from blood to cerebrospinal fluid (CSF). By use of a standard time-cycled pressure-limited infant respirator, mean airway pressure (Paw) was increased from approximately 3 to 17 cmH2O. Urea and albumin transfer into the brain were unchanged with increased Paw. Sodium transport decreased significantly in all brain regions, while sucrose transfer was increased in the cerebrum [transfer constant (Kin) = 3.5 +/- 0.04 vs. 9.9 +/- 1.0 cm3.g-1.s-1.10(6)] at the increased Paw. Transport of urea nd sodium from blood to CSF decreased to half of control values with increased Paw. Thus, in newborn pigs, increasing Paw selectively alters blood-to-brain transport. In addition, movement of tracers from blood to CSF was severely restricted, possibly by a decrease in CSF production. It appears likely that the increased cerebral venous pressure causes the observed changes in tracer transport. Such altered blood-to-brain transport could adversely affect neuronal function.
Mirro
R
R
Department of Pediatrics, University of Tennessee, Memphis 38163.
Leffler
C W
CW
Armstead
W M
WM
Busija
D W
DW
D000818:Animals; D000831:Animals, Newborn; D001693:Biological Transport, Active; D001812:Blood-Brain Barrier / Q000502:physiology*; D002555:Cerebrospinal Fluid / Q000502:physiology; D007700:Kinetics; D011175:Positive-Pressure Respiration; D012964:Sodium / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism; D014508:Urea / Q000378:metabolism
D013395:Sucrose; D014508:Urea; D012964:Sodium