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.
Department of Medical Physiology, Faculty of Medicine Belgrade, Yugoslavia.
B V
BV
Zlokovic
M B
MB
Segal
H
H
Davson
R M
RM
Jankov
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