Passage of delta sleep-inducing peptide (DSIP) across the blood-cerebrospinal fluid barrier.
Unidirectional flux of 125I-labeled DSIP at the blood-tissue interface of the blood-cerebrospinal fluid (CSF) barrier was studied in the perfused in situ choroid plexuses of the lateral ventricles of the sheep. Arterio-venous loss of 125I-radioactivity suggested a low-to-moderate permeability of the choroid epithelium to the intact peptide from the blood side. A saturable mechanism with Michaelis-Menten type kinetics with high affinity and very low capacity (approximate values: Kt = 5.0 +/- 0.4 nM; Vmax = 272 +/- 10 fmol.min-1) was demonstrated at the blood-tissue interface of the choroid plexus. The clearance of DSIP from the ventricles during ventriculo-cisternal perfusion in the rabbit indicated no significant flux of the intact peptide out of the CSF. The results suggest that DSIP crosses the blood-CSF barrier, while the system lacks the specific mechanisms for removal from the CSF found with most, if not all, amino acids and several peptides.
Zlokovic
B V
BV
Department of Medical Physiology, Faculty of Medicine Belgrade, Yugoslavia.
Segal
M B
MB
Davson
H
H
Jankov
R M
RM
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002831:Choroid Plexus / Q000378:metabolism; D003701:Delta Sleep-Inducing Peptide / Q000097:blood / Q000134:cerebrospinal fluid / Q000493:pharmacokinetics*; D005260:Female; D007457:Iodine Radioisotopes; D007700:Kinetics; D008297:Male; D009928:Organ Specificity; D010539:Permeability; D012756:Sheep
D007457:Iodine Radioisotopes; D003701:Delta Sleep-Inducing Peptide