Inhibition of spontaneous transmitter release by the membrane ligand cationized ferritin.
Exposure of the frog neuromuscular junction to cationized ferritin (200 micrograms ml-1) results in a reduction in MEPP frequency of approximately 25% within 10 min. This effect is not dependent on extracellular Ca2+, and identical results are obtained in salines buffered with EGTA. It is suggested that cationized ferritin does not inhibit transmitter release via a reduction in the intracellular Ca2+ concentration, but exerts its effect by a direct action on exocytosis. A mode of action is proposed. Unlike Con A, cationized ferritin is unable to suppress the stimulation of spontaneous release caused by high osmolarity.
D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology; D005293:Ferritins / Q000494:pharmacology*; D066298:In Vitro Techniques; D008024:Ligands; D009045:Motor Endplate / Q000187:drug effects; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009994:Osmolar Concentration; D011108:Polymers / Q000494:pharmacology; D011896:Rana temporaria
D008024:Ligands; D018377:Neurotransmitter Agents; D011108:Polymers; C010297:polycationic ferritin; D003208:Concanavalin A; D005293:Ferritins