Document Detail

Role of calcium ions in the formation and release of low-molecular-weight substances from optic nerve terminals.
MedLine Citation:
PMID:  6162113     Owner:  NLM     Status:  MEDLINE    
Retinal proteins were labeled by intraocular injections of radioactive amino acids. Tissue slices of the superior colliculus (SC) were prepared 18-20 hr later, i.e., when the rapid phases of the axonal transport had reached the SC terminals. The effect of depolarizing pulses of high K and of Ca withdrawal on the scretion of radioactivity was studied in a perfusion system. The effluents were separated into a trichloroacetic acid (TCA) precipitable fraction and a TCA-soluble fraction. High K evoked a release of TCA-soluble radioactivity when [(3)H]glycine, [(3)H]leucine, or [(3)H]proline were used as protein precursors. Small changes occurred for TCA-precipitable fractions. The evoked release of radioactivity was Ca dependent and particularly prominent after labeling with [(3)H]glycine. Ca withdrawal increased the efflux of exogenous GABA, primary amines, and TCA-precipitable radioactivity but not of TCA-soluble radioactivity when normal media were used. The formation of TCA-soluble radioactivity was measured by incubating combined homogenates of SC and the lateral geniculate body (LGB), containing labeled proteins transported by the slow or rapid phase. The proteolytic activity was highly Ca dependent, for the rapidly transported proteins the half maximum was at approximately 0.1 mM Ca. The formation of TCA-soluble radioactivity was inhibited by p-chloromercuriphenylsulfonic acid (PCMS). Other divalent cations could not substitute for Ca. The rate of formation of TCA-soluble radioactivity and the influence of Ca ions was smaller when proteins of the slow phase were used as substrate.
M Sandberg; A Hamberger; I Jacobson; J O Karlsson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Neurochemical research     Volume:  5     ISSN:  0364-3190     ISO Abbreviation:  Neurochem. Res.     Publication Date:  1980 Nov 
Date Detail:
Created Date:  1981-04-13     Completed Date:  1981-04-13     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  7613461     Medline TA:  Neurochem Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1185-98     Citation Subset:  IM    
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MeSH Terms
Amino Acids / metabolism
Axonal Transport
Axons / metabolism
Biological Transport
Calcium / pharmacology*
Molecular Weight
Nerve Endings / metabolism
Nerve Tissue Proteins / metabolism*
Optic Nerve / metabolism*
Superior Colliculi / metabolism*
Trichloroacetic Acid
Reg. No./Substance:
0/Amino Acids; 0/Nerve Tissue Proteins; 7440-70-2/Calcium; 76-03-9/Trichloroacetic Acid

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

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