Long-term use-dependent enhancement of impulse-induced exocytosis by adrenaline at frog motor nerve terminals.
Adrenaline (5-20 microM) use-dependently increased end-plate potentials (EPPs) in normal Ringer solution (containing d-tubocurarine to partially block acetylcholine receptors) and a low Ca2+, high Mg2+ solution for more than several hours and decreased the coefficient of variation of EPP amplitude in the latter solution in frog neuromuscular junctions. The amplitude and frequency of miniature EPPs and impulse-induced increases in intraterminal Ca2+ concentration were unaffected. Adrenaline thus causes sustained enhancement of impulse-induced exocytosis by acting at a mechanism of exocytosis downstream to Ca2+ entry.
Huang
S M
SM
Department of Physiology, Nagoya University, School of Medicine, Japan.
Akita
T
T
Kitamura
A
A
Nakayama
S
S
Tokuno
H
H
Kuba
K
K
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects* / Q000502:physiology; D005089:Exocytosis / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D009045:Motor Endplate / Q000187:drug effects / Q000502:physiology*; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation*; D009411:Nerve Endings / Q000187:drug effects / Q000502:physiology*; D011898:Ranidae; D013997:Time Factors; D014403:Tubocurarine / Q000494:pharmacology
D002413:Cations, Divalent; D008274:Magnesium; D002118:Calcium; D014403:Tubocurarine; D004837:Epinephrine