PMID- 6982330
OWN - NLM
STAT- MEDLINE
DCOM- 19821216
LR  - 20190511
IS  - 0022-3751 (Print)
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Linking)
VI  - 328
DP  - 1982 Jul
TI  - Effects of calcium and strontium in the process of acetylcholine release from 
      motor nerve endings.
PG  - 547-62
AB  - 1. The effects of Ca and Sr ions on synchronous acetyleholine (ACh) secretion 
      (the impulsive, physiologically functional form of secretion which produces an 
      end-plate potential in response to a single nerve impulse) and on asynchronous 
      ACh secretion (the delayed, residual increase in miniature end-plate potential 
      frequency evoked by repetitive nerve impulses or by accumulation of intracellular 
      divalent cations) were studied at frog neuromuscular junctions.2. In a comparison 
      of their extracellular effects, Ca was far more effective than Sr in supporting 
      synchronous ACh secretion but less effective than Sr in mediating asynchronous 
      release evoked by repetitive nerve impulses.3. In studies of their intracellular 
      effects, Sr and Ca were delivered to the nerve terminal cytoplasm using liposomes 
      as a vehicle. Ca-containing liposomes, although producing effects on asynchronous 
      ACh secretion that were indistinguishable from those of equimolar Sr-containing 
      liposomes, were more effective than Sr-containing liposomes in increasing 
      synchronous release.4. Extracellular Ca behaved as a potent competitve inhibitor 
      of asynchronous, neurally evoked release mediated by Sr. In contrast, 
      intracellular Ca (i.e. liposomal Ca), whilst increasing synchronous ACh release, 
      failed to antagonize evoked asynchronous release.5. The results demonstrate that 
      synchronous and asynchronous secretion have different sensitivities to 
      alterations in intracellular divalent cation concentrations. It is suggested that 
      selectivity for Ca over Sr may occur at intraterminal sites responsible for 
      synchronous ACh secretion but not at sites responsible for asynchronous ACh 
      release. Furthermore, Ca appears to bind with high affinity as an antagonist at 
      the external surface of the nerve ending. These results are discussed in 
      conjunction with current theories of depolarization-secretion coupling.
FAU - Mellow, A M
AU  - Mellow AM
FAU - Perry, B D
AU  - Perry BD
FAU - Silinsky, E M
AU  - Silinsky EM
LA  - eng
GR  - NS 12782/NS/NINDS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
RN  - 0 (Liposomes)
RN  - N9YNS0M02X (Acetylcholine)
RN  - SY7Q814VUP (Calcium)
RN  - YZS2RPE8LE (Strontium)
SB  - IM
MH  - Acetylcholine/*metabolism
MH  - Animals
MH  - Binding Sites
MH  - Calcium/metabolism/*pharmacology
MH  - In Vitro Techniques
MH  - Kinetics
MH  - Liposomes/pharmacology
MH  - Membrane Potentials/drug effects
MH  - Motor Endplate/drug effects/*physiology
MH  - Muscles/physiology
MH  - Neuromuscular Junction/*physiology
MH  - Rana pipiens
MH  - Strontium/*pharmacology
PMC - PMC1225677
EDAT- 1982/07/01 00:00
MHDA- 1982/07/01 00:01
PMCR- 1982/01/01
CRDT- 1982/07/01 00:00
PHST- 1982/07/01 00:00 [pubmed]
PHST- 1982/07/01 00:01 [medline]
PHST- 1982/07/01 00:00 [entrez]
PHST- 1982/01/01 00:00 [pmc-release]
AID - 10.1113/jphysiol.1982.sp014283 [doi]
PST - ppublish
SO  - J Physiol. 1982 Jul;328:547-62. doi: 10.1113/jphysiol.1982.sp014283.