Absorptive-mediated endocytosis of cationized albumin and a beta-endorphin-cationized albumin chimeric peptide by isolated brain capillaries. Model system of blood-brain barrier transport

Journal Article · Thu Nov 05 04:00:00 EST 1987 · J. Biol. Chem.; (United States)

OSTI ID:5786579

Kumagai, A K; Eisenberg, J B; Pardridge, W M

Cationized albumin (pI greater than 8), unlike native albumin (pI approximately 4), enters cerebrospinal fluid (CSF) rapidly from blood. This suggests that a specific uptake mechanism for cationized albumin may exist at the brain capillary wall, i.e. the blood-brain barrier. Isolated bovine brain capillaries rapidly bound cationized (/sup 3/H)albumin and approximately 70% of the bound radioactivity was resistant to mild acid wash, which is assumed to represent internalized peptide. Binding was saturable and a Scatchard plot gave a maximal binding capacity (Ro) = 5.5 +/- 0.7 micrograms/mgp (79 +/- 10 pmol/mgp), and a half-saturation constant (KD) = 55 +/- 8 micrograms/ml (0.8 +/- 0.1 microM). The binding of cationized (/sup 3/H)albumin (pI = 8.5-9) was inhibited by protamine, protamine sulfate, and polylysine (molecular weight = 70,000) with a Ki of approximately 3 micrograms/ml for all three proteins. The use of cationized albumin in directed delivery of peptides through the blood-brain barrier was examined by coupling (/sup 3/H)beta-endorphin to unlabeled cationized albumin (pI = 8.5-9) using the bifunctional reagent, N-succinimidyl 3-(2-pyridyldithio)proprionate. The (/sup 3/H)beta-endorphin-cationized albumin chimeric peptide was rapidly bound and endocytosed by isolated bovine brain capillaries, and this was inhibited by unlabeled cationized albumin but not by unconjugated beta-endorphin or native bovine albumin. Cationized albumin provides a new tool for studying absorptive-mediated endocytosis at the brain capillary and may also provide a vehicle for directed drug delivery through the blood-brain barrier.

• OSTI ID: 5786579
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 262:31; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALBUMINS
ANIMALS
AUTORADIOGRAPHY
BIOCHEMICAL REACTION KINETICS
BLOOD VESSELS
BLOOD-BRAIN BARRIER
BODY
BRAIN
CAPILLARIES
CARDIOVASCULAR SYSTEM
CATIONS
CATTLE
CENTRAL NERVOUS SYSTEM
CHARGED PARTICLES
COAGULANTS
DOMESTIC ANIMALS
DRUGS
HEMATOLOGIC AGENTS
HEPARIN ANTAGONISTS
INHIBITION
IONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE TRANSPORT
NERVOUS SYSTEM
NUCLEOPROTEINS
ORGANIC COMPOUNDS
ORGANS
PEPTIDES
PHAGOCYTOSIS
PROTAMINES
PROTEINS
REACTION KINETICS
RUMINANTS
TRITIUM COMPOUNDS
VERTEBRATES