[Interactions between liposomes and synaptosomes].
In continuing experiments to determine the basis of presynaptic modulation, rat cortical synaptosomes were employed and transmembrane calcium fluxes were determined with a metalocromophoric dye, Arsenazo III. The intracellular free Ca2+ concentrations show complex fluctuations in time and space in response to a variety of stimuli, acting as a pluripotent signal for many neuronal functions. Depolarisation of synaptosomes by K+ 20 mM determined calcium influx in cortical synaptosomes, mainly mediated by the Q type Ca2+ channels, with a minor participation of the N type channels. The administration protocol for the polyamines, revealed that agmatine, spermine, spermidine, putresceine and cadaverine reduce, in variable proportions, the K(+)-induced Ca2+ influx, in synaptosomal preparations. The results plead for the ability of agmatine and spermine to modulate Ca2+ fluxes in synaptosomes, both from the interior and exterior side. Moreover, rigidization of the synaptosomal membrane (by cholesterol-enriched liposomes administration) do not significantly influences K(+)-induced Ca2+ influx in synaptosomal preparations.
Foia
L
L
Disciplina de Biochimie, Facultatea de Medicină, Facultatea de Medicină Stomatologică, Universitatea de Medicină şi Farmacie Gr.T. Popa Iaşi.
Costuleanu
M
M
Costuleanu
N
N
Pavel
M
M
Ungureanu
D
D
Filip
F
F
D000818:Animals; D001150:Arsenazo III / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000648:ultrastructure; D004396:Coloring Agents / Q000494:pharmacology; D008081:Liposomes / Q000378:metabolism*; D008297:Male; D011073:Polyamines / Q000494:pharmacology*; D017729:Presynaptic Terminals / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D013096:Spermine / Q000494:pharmacology; D013574:Synaptosomes / Q000378:metabolism* / Q000648:ultrastructure
D015220:Calcium Channels; D004396:Coloring Agents; D008081:Liposomes; D011073:Polyamines; D001150:Arsenazo III; D013096:Spermine