20.500.12556/RUL-182933 Equinatoxin II how a cationic pore-forming sea anemone toxin drives nodal swelling of myelinated nerve fibers This study was performed to elucidate the mechanism underpinning the nodal swelling induced by equinatoxin II (EqtII), a cation-selective pore-forming toxin derived from the sea anemone Actinia equina. Experiments were conducted using frog myelinated nerve fibers as a model system. Application of EqtII led to an approximately two-fold increase in the nodal volume of myelinated axons, but only when extracellular Ca2+ was present. Replacing extracellular Cl− with isethionate had no measurable effect on this response, whereas substitution of NaCl with either sucrose or LiCl, an established Na+/Ca2+ exchanger (NCX) inhibitor, abolished the swelling. The persistence of the effect in the presence of tetrodotoxin indicates that voltage-gated Na+ channels are not involved in the underlying mechanism. Our data suggest that Ca2+ influx through EqtII-induced membrane pores raises intracellular Ca2+ levels, thereby stimulating the NCX in its forward-operating mode. This process promotes Ca2+ extrusion in exchange for Na+ entry. The resulting accumulation of intracellular Na+ increases osmotic pressure within the axon, leading to water influx and nodal swelling. axonal swelling cationic pore-forming peptide confocal laser scanning microscopy equinatoxin II ionic mechanisms myelinated nerve fiber otekanje aksonov kationski peptid ki tvori pore konfokalna laserska vrstična mikroskopija ekvinatoksin II ionski mehanizmi mielinizirano živčno vlakno true false true Angleški jezik Slovenski jezik Članek v reviji 2026-05-29 04:36:28 2026-05-29 07:21:28 2026-05-30 04:58:29 0000-00-00 00:00:00 2026 0 0 17 str. iss. 5, art. 187 Vol. 24 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 615.9:577.15:616.8 1660-3397 10.3390/md24050187 279259907 Equinatoxin-Frangez.pdf Equinatoxin-Frangez.pdf 1 1067744A4EAEDD55B8165E89E610EE54 2c484c3e191e40caaf38cba1744256527b87a9a18d02bb78c6633d0cfec0d508 c9405711-5b1d-11f1-b0ab-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=234641 https://www.mdpi.com/1660-3397/24/5/187 1 dda02075-5b06-11f1-b0ab-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=234625 Veterinarska fakulteta Medicinska fakulteta 0 0 0