Possible Interaction: 4-Aminopyridine and Calcium Supplement

“ 4-AP , a well-known inhibitor of Kv channels, also increases Ca 2 + concentration in the caveolae vesicles via Cav1.2 channels, reverse-mode NCX-1 and Nav1.5 channels by phosphorylation independent modulation of Kv1.5 channels without the involvement of PKCζ–NADPH oxidase–PKCα signaling axis.”

“After 4-aminopyridine washout, current recovery from block was slower in the presence than in the absence of calcium.”

“The concentration-effect curve of 4-aminopyridine was shifted to the left in the presence of 2mM calcium compared to 0 calcium.”

“These results showed that extracellular calcium modulated the inhibitory potency of 4-aminopyridine on Kv current in vascular myocytes.”

“ 4-AP might enhance the flux of calcium ions into nerve terminals during depolarization, and thus increase the release of noradrenaline, whereas this process might be of less importance in the dopamine and the 5-hydroxytryptamine nerves.”

“In the presence of elevated potassium, 4-aminopyridine or tetraethylammonium, the secretagogue efficacy of calcium (but not barium) was markedly increased.”

“4-aminopyridine 4-AP ) strongly enhanced presynaptic Ca2+-influx but only marginally increased Ca2+ -entry into the postsynaptic neurones.”

“This effect is augmented in 4-aminopyridine (4-AP; 1 mM), which dramatically increases the calcium and presumably sodium load during the tetanus.”

“With 4-aminopyridine we recorded an acceleration of neuronal activity, and in most cells a slow depolarization (mean 6.8 mV), during the ca.”

“These results support the hypothesis that 4-aminopyridine increases presynaptic nerve terminal permeability of calcium and thus the release of noradrenaline.”

“It is suggested that 4-AP enhances Ca influx either pre- or postsynaptically and thereby increases LTP.”

“ 4-Aminopyridine (1 mM) markedly suppresses the rapid early repolarization of this preparation at post-rest excitations and the loss of contractility at post-rest stimulation from the rested state; during a post-stimulatory potentiation sequence at low calcium , replenishment of extracellular calcium takes several post- stimulatory excitations.”