Linked Life Data

1556600

Source:http://linkedlifedata.com/resource/pubmed/id/1556600

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1992-5-6
pubmed:abstractText
Rabbit retinas were isolated from the eye and maintained in vitro. When they were incubated for 60 min in the presence of 3H-GABA, subsequent autoradiography showed radioactivity to be present primarily in amacrine cells. Under these conditions, most of the radioactivity contained in the retinas remained in the chemical form of GABA. Autoradiography and immunohistochemistry of alternate sections showed the amacrine cells that accumulate 3H-GABA to be the same cells that contain endogenous GABA immunoreactivity. These include the starburst cells, the indoleamine-accumulating cells, and other, as yet unidentified amacrine cells. The localization confirms previous immunohistochemical findings. When retinas containing 3H-GABA were expressed to elevated concentrations of K+, their content of 3H-GABA decreased. Autoradiography showed a reduced 3H-GABA content in all of the cells that contained 3H-GABA. Since those include the starburst cells, previously shown to be cholinergic, the finding demonstrates that the starburst cells release both ACh and GABA. Retinas simultaneously labeled with 14C-GABA and 3H-ACh were superfused, and the release of radioactive compounds from the retina was studied. Depolarization by elevated K+ caused an increased recovery of both ACh and GABA in the superfusate, but the predominant mechanisms of their release appeared to be different. The stimulated release of ACh was entirely Ca2+ dependent, while the release of radioactivity originating from GABA was much less so. A concentration-dependent counterflux (homoexchange) of intracellular GABA was demonstrated by raising the extracellular concentration of GABA (or nipecotic acid). These results suggest that a large outward flux of GABA occurs via the GABA transporter, probably by the potential-sensitive mechanism studied by Schwartz (1982, 1987). Stimulation of double-labeled retinas by flashing light or moving bars always increased the release of ACh, and the release was entirely dependent on the presence of extracellular Ca2+. Stimulation with light never caused a detectable release of GABA. This was unexpected, since the two neurotransmitters are present in the same amacrine cells: stimulation adequate to release one neurotransmitter should release both.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0270-6474
pubmed:author
pubmed:issnType
Print
pubmed:volume
12
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1394-408
pubmed:dateRevised
2010-3-22
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Co-release of acetylcholine and GABA by the starburst amacrine cells.
pubmed:affiliation
Department of Physiology, Harvard Medical School, Boston, Massachusetts 02114.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.