Choline: High Affinity Transport into Synaptosomes of Rat Brain.
Abstract
The accumulation of (3H) choline into synaptosome-enriched homogenates of rat corpus striatum, cerebral cortex, and cerebellum was studied at (3H) choline concentrations varying from 0.5 to 100 micrometers M. The accumulation of (3H) choline in these brain regions was saturable. Kinetic analysis of the accumulation of the radiolabel was performed by double-reciprocal plots and by least-squares iterative fitting of a substrate-velocity curve to the data. With both of these techniques, the data were best satisfied by two transport components, a high-affinity uptake system with Km values of 1.4 micrometers M (corpus striatum), and 3.1 micrometers M (cerebral cortex), and a low-affinity uptake system with Km values of 93 and 33 micrometers M for these two brain regions. In the cerebellum, choline was accumulated only by the low-affinity system. When striatal homogenates were fractioned further into synaptosomes and mitochondria and incubated with varying concentrations of (3H) choline, the high-affinity component of choline uptake was localized to the synaptosomal fraction. A variety of evidence suggests that the high-affinity transport represents a selective accumulation of choline by cholinergic neurons, while the low-affinity uptake system has some less specific function. (Modified author abstract)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1974
- Accession Number
- AD0774813
Entities
People
- Henry I. Yamamura
- Lea M. Somers
- Louis A. Fedele
- Tommy L. Gardner