Biomaterial Database

Developmental changes in blood-brain barrier potassium permeability in the rat: relation to brain growth. 1995

R F Keep, and S R Ennis, and M E Beer, and A L Betz

Department of Surgery (Neurosurgery), University of Michigan, Ann Arbor 48109, USA.

1. The potassium permeability of the blood-brain barrier (BBB) was determined in anaesthetized rats aged between 21 days gestation and adult using 86Rb+ as a marker for potassium. 2. The brain influx rate constant for 86Rb+ was high in fetal cortex at 21 days gestation (42.5 +/- 4.3 microliters g-1 min-1) but had decreased markedly by just after birth (12.2 +/- 0.6 microliters g-1 min-1). There was a further, gradual, postnatal decline to 7.0 +/- 0.3 microliters g-1 min-1 by 50 days after birth. 3. Developmental changes in passive BBB permeability were examined over the same age range using 14[C]urea. These studies showed similar developmental changes in influx rate to those found for 86Rb+. Specifically, a marked perinatal decline followed by a more gradual postnatal fall. Thus, the changes in potassium permeability probably reflect a decrease in the BBB paracellular leak during development. 4. The changes in BBB permeability coincide with changes in the rate of brain growth and the associated rate of brain potassium accumulation. As the potassium permeability properties of the adult BBB would provide insufficient potassium influx to meet the requirement associated with fetal brain growth, it is suggested that need for potassium may be the reason for the greater BBB permeability early in development.

UI	MeSH Term	Description	Entries
D010539	Permeability	Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.	Permeabilities
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D001812	Blood-Brain Barrier	Specialized non-fenestrated tightly-joined ENDOTHELIAL CELLS with TIGHT JUNCTIONS that form a transport barrier for certain substances between the cerebral capillaries and the BRAIN tissue.	Brain-Blood Barrier,Hemato-Encephalic Barrier,Barrier, Blood-Brain,Barrier, Brain-Blood,Barrier, Hemato-Encephalic,Barriers, Blood-Brain,Barriers, Brain-Blood,Barriers, Hemato-Encephalic,Blood Brain Barrier,Blood-Brain Barriers,Brain Blood Barrier,Brain-Blood Barriers,Hemato Encephalic Barrier,Hemato-Encephalic Barriers
D001921	Brain	The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.	Encephalon
D002540	Cerebral Cortex	The thin layer of GRAY MATTER on the surface of the CEREBRAL HEMISPHERES that develops from the TELENCEPHALON and folds into gyri and sulci. It reaches its highest development in humans and is responsible for intellectual faculties and higher mental functions.	Allocortex,Archipallium,Cortex Cerebri,Cortical Plate,Paleocortex,Periallocortex,Allocortices,Archipalliums,Cerebral Cortices,Cortex Cerebrus,Cortex, Cerebral,Cortical Plates,Paleocortices,Periallocortices,Plate, Cortical
D005260	Female		Females
D005333	Fetus	The unborn young of a viviparous mammal, in the postembryonic period, after the major structures have been outlined. In humans, the unborn young from the end of the eighth week after CONCEPTION until BIRTH, as distinguished from the earlier EMBRYO, MAMMALIAN.	Fetal Structures,Fetal Tissue,Fetuses,Mummified Fetus,Retained Fetus,Fetal Structure,Fetal Tissues,Fetus, Mummified,Fetus, Retained,Structure, Fetal,Structures, Fetal,Tissue, Fetal,Tissues, Fetal
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000831	Animals, Newborn	Refers to animals in the period of time just after birth.	Animals, Neonatal,Animal, Neonatal,Animal, Newborn,Neonatal Animal,Neonatal Animals,Newborn Animal,Newborn Animals