Biomaterial Database

Uptake of radiocalcium by nerve endings isolated from rat brain: kinetic studies. 1980

J Gripenberg, and E Heinonen, and S E Jansson

1 The uptake of radiocalcium by nerve-ending particles isolated from rat brain was studied in vitro by means of a rapid lanthanum quenching technique. 2 The observed uptake fits a theoretical three-compartment model with two separate uptake phases, a fast, initial phase followed by a late, slow phase. This holds true during control conditions as well as during high-potassium stimulation. 3 The uptake as a function of the external calcium concentration can be described in terms of Michaelis-Menten kinetics during high-potassium stimulation. Under control conditions the fit is clearly applicable but statistically not as good as during potassium stimulation. 4 The affinity for the uptake of calcium remains unchanged under control conditions while during high-potassium stimulation the affinity drastically decreases during the late, slow phase of uptake. 5 During high-potassium stimulation the maximal velocity of calcium uptake is twice that during control conditions. This holds true for both the fast and the slow phases of the uptake. 6 Mg2+ has an inhibitory effect on the uptake, the inhibition being more effective during high-potassium stimulation. Tetrodotoxin has a slight inhibitory effect additional to that extended by Mg2+ during the initial phase of uptake into high potassium stimulated synaptosomes.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
D008297	Male		Males
D009411	Nerve Endings	Branch-like terminations of NERVE FIBERS, sensory or motor NEURONS. Endings of sensory neurons are the beginnings of afferent pathway to the CENTRAL NERVOUS SYSTEM. Endings of motor neurons are the terminals of axons at the muscle cells. Nerve endings which release neurotransmitters are called PRESYNAPTIC TERMINALS.	Ending, Nerve,Endings, Nerve,Nerve Ending
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
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002132	Calcium Radioisotopes	Unstable isotopes of calcium that decay or disintegrate emitting radiation. Ca atoms with atomic weights 39, 41, 45, 47, 49, and 50 are radioactive calcium isotopes.	Radioisotopes, Calcium
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
D013574	Synaptosomes	Pinched-off nerve endings and their contents of vesicles and cytoplasm together with the attached subsynaptic area of the membrane of the post-synaptic cell. They are largely artificial structures produced by fractionation after selective centrifugation of nervous tissue homogenates.	Synaptosome
D013779	Tetrodotoxin	An aminoperhydroquinazoline poison found mainly in the liver and ovaries of fishes in the order TETRAODONTIFORMES, which are eaten. The toxin causes paresthesia and paralysis through interference with neuromuscular conduction.	Fugu Toxin,Tarichatoxin,Tetradotoxin,Toxin, Fugu