Linked Life Data

8325848

Source:http://linkedlifedata.com/resource/pubmed/id/8325848

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
20
pubmed:dateCreated
1993-8-12
pubmed:abstractText
Exocytotic release of vesicular catecholamine from individual bovine adrenal medullary cells was detected with carbon fiber microelectrodes. Release was elicited from cells permeabilized with 20 microM digitonin in extracellular solutions of pH 5.5, 7.4, or 8.2, and with 100 microM nicotine at pH 7.4. Release detected amperometrically with a 6-microns radius electrode and 1-micron cell-electrode spacing was qualitatively similar for each pH and stimulus. However, amperometric detection with smaller electrodes (radius = 1 micron), cyclic voltammetry, or increased cell-electrode spacing with the larger electrode all resulted in a severe reduction in size and frequency of spikes detected at pH 5.5. Thus, the existence of a steep catecholamine concentration gradient at the cell surface is necessary to cause dissociation of the vesicular matrix at low extracellular pH. At an extracellular pH of 7.4, the distribution of amperometric spike widths measured with a 1-micron cell-electrode spacing was found to be inconsistent with that predicted for diffusional dispersion during transport from the cell surface to the electrode. Both of these results agree with the hypotheses that the chromaffin vesicle matrix normally exists in an aggregated state that can be dissociated by a chemical driving force. Some of the spikes exhibit a pre-spike feature. These were present more often following permeabilization in acidic pH as opposed to more alkaline solutions, and were most prevalent following exposure to nicotine at pH 7.4. The variability in the occurrence of the pre-spike feature suggests it originates from free catecholamine within the vesicle, since the molar fraction bound by the vesicular matrix is regulated by the pH-dependent conformation and Ca(2+)-dependent binding affinity of chromogranin A, a major protein in the vesicle.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
268
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14694-700
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Temporal characteristics of quantal secretion of catecholamines from adrenal medullary cells.
pubmed:affiliation
Department of Chemistry, University of North Carolina, Chapel Hill 27599-3290.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.