Document Detail

Passive ion permeability of the chromaffin-granule membrane.
MedLine Citation:
PMID:  23117     Owner:  NLM     Status:  MEDLINE    
'Ghosts' of bovine chromaffin granules, in which the complex mixture of proteins and solutes normally found in the granule matrix is replaced by buffered sucrose are osmotically sensitive. They shrink when the osmotic pressure of the suspension medium is increased, and swell if solute entry is facilitated by the addition of ionophores. Swelling in the presence of ionophores has been used to investigate the passive ion permeability of these membranes. They have a very low permeability to K+ ions (of the order of 10(-10) cm/s); their permeability to protons, Na+ and choline ions is too low to be detected by these methods. Their passive permeability to anions decreases in the order: CNS- greater than I- greater than CCl3CO2- greater than Br- greater than Cl- greater than SO4(2)- greater than CH3CO2-, HCO3-, F-, PO4(3)- the permeability to hiocyanate being of the order of 10(-7) cm/s. Coupled proton and anion entry is extremely slow, except for weak acids. Fluoride, unexpectedly, also appears to enter rapidly when proton/K+ exchange is facilitated by nigericin. In the presence of K+ salts, nigericin, like valinomycin, induces lysis of intact granules, an effect that is not dependent on the presence of a permeant anion, but is dependent on the pH gradient across the membrane.
J H Phillips
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  The Biochemical journal     Volume:  168     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1977 Nov 
Date Detail:
Created Date:  1978-02-23     Completed Date:  1978-02-23     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  289-97     Citation Subset:  IM    
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MeSH Terms
Chromaffin Granules / drug effects,  metabolism*
Chromaffin System / metabolism*
Hydrogen-Ion Concentration
Ionophores / pharmacology
Nigericin / pharmacology
Potassium / metabolism
Valinomycin / pharmacology
Reg. No./Substance:
0/Ionophores; 0/Ions; 0/Protons; 2001-95-8/Valinomycin; 28380-24-7/Nigericin; 7440-09-7/Potassium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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