Biomaterial Database

On the mechanism by which extracellular sodium depletion causes 5-hydroxytryptamine release from rat brain synaptosomes. 1989

K J Collard

Department of Physiology, University of Wales College of Cardiff, U.K.

The release of 3H-labelled 5-hydroxytryptamine (5-HT) from preloaded and superfused rat forebrain synaptosomes in response to extracellular Na+ depletion was studied. In the absence of monoamine oxidase inhibitors, the release of [3H]-5-HT caused by Na+ depletion was not affected by immobilizers of the plasma membrane 5-HT carrier. The release of [3H]-5-HT in response to Na+ depletion was also either independent of, or inversely related to the concentration of extracellular Ca2+ depending on the degree to which extracellular Na+ was reduced. The efflux of 45Ca2+ from prelabelled synaptosomes was decreased by Na+ reduction but the amplitude of the changes in 45Ca2+ efflux did not totally correlate with the changes in [3H]-5-HT efflux under the same experimental conditions. These results suggest that the release of [3H]-5-HT caused by Na+ depletion in drug-free synaptosomes is not mediated by 5-HT efflux through the plasma membrane carrier, nor to changes in cytosolic Ca2+ consequent to changes in Ca2+ fluxes across the plasma membrane. The results have been tentatively explained as an elevation of spontaneous 5-HT efflux caused by an increase in membrane fluidity mediated by the ionic manipulations used to produce the Na+-depleted media.

UI	MeSH Term	Description	Entries
D009526	Nialamide	An MAO inhibitor that is used as an antidepressive agent.
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
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D005110	Extracellular Space	Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.	Intercellular Space,Extracellular Spaces,Intercellular Spaces,Space, Extracellular,Space, Intercellular,Spaces, Extracellular,Spaces, Intercellular
D005473	Fluoxetine	The first highly specific serotonin uptake inhibitor. It is used as an antidepressant and often has a more acceptable side-effects profile than traditional antidepressants.	Fluoxetin,Fluoxetine Hydrochloride,Lilly-110140,N-Methyl-gamma-(4-(trifluoromethyl)phenoxy)benzenepropanamine,Prozac,Sarafem,Lilly 110140,Lilly110140
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
D012701	Serotonin	A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.	5-HT,5-Hydroxytryptamine,3-(2-Aminoethyl)-1H-indol-5-ol,Enteramine,Hippophaine,Hydroxytryptamine,5 Hydroxytryptamine
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23
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