title: Molecular pharmacology of the amiloride analog 3-amino-6-chloro-5-[(4-chloro-benzyl)amino]-n-[[(2,4-dimethylbenzyl)-amino]iminomethyl]-pyrazinecarboxamide (CB-DMB) as a pan inhibitor of the Na+-Ca2+ exchanger isoforms NCX1, NCX2, and NCX3 in stably transfected cells.
abstract: With the help of single-cell microflorimetry, (45)Ca(2+) radiotracer fluxes, and patch-clamp in whole-cell configuration, we examined the effect of the amiloride derivative 3-amino-6-chloro-5-[(4-chloro-benzyl)amino]-N-[[(2,4-dimethylbenzyl)amino]iminomethyl]-pyrazinecarboxamide (CB-DMB) on the activity of the three isoforms of the Na(+)/Ca(2+) exchanger (NCX) and on several other membrane currents including voltage- and pH-sensitive ones. This amiloride analog suppressed the bidirectional activity of all NCX isoforms in a concentration-dependent manner. The IC(50) values of CB-DMB were in the nanomolar range for the outward and the inward components of the bidirectional NCX1, NCX2, and NCX3 activity. Deletion mutagenesis showed that CB-DMB inhibited NCX activity mainly at level of the f-loop but not through the interaction with Gly833 located at the level of the alpha(2) repeat. On the other hand, CB-DMB suppressed in the micromolar range the other plasma membrane currents encoded by voltage-dependent Ca(2+) channels, tetrodotoxin-sensitive Na(+) channels, and pH-sensitive ASIC1a. Collectively, the data of the present study showed that CB-DMB, when used in the nanomolar range, is one of the most potent compounds that can block the activity of the three NCX isoforms when they work both in the forward and in the reverse modes of operation without interfering with other ionic channels.
authors: Department of Neuroscience, University of Naples "Federico II", Italy.
authors: Agnese
authors: A
authors: Secondo
authors: Anna
authors: A
authors: Pannaccione
authors: Pasquale
authors: P
authors: Molinaro
authors: Paolo
authors: P
authors: Ambrosino
authors: Pellegrino
authors: P
authors: Lippiello
authors: Alba
authors: A
authors: Esposito
authors: Maria
authors: M
authors: Cantile
authors: Priti R
authors: PR
authors: Khatri
authors: Daniela
authors: D
authors: Melisi
authors: Gianfranco
authors: G
authors: Di Renzo
authors: Lucio
authors: L
authors: Annunziato
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D006224:Cricetinae; D004285:Dogs; D006801:Humans; D020033:Protein Isoforms / Q000037:antagonists & inhibitors / Q000502:physiology; D051381:Rats; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors* / Q000502:physiology; D014162:Transfection / Q000379:methods
chemical_list: D020033:Protein Isoforms; C110927:Slc8a2 protein, rat; C491102:Slc8a3 protein, rat; D019831:Sodium-Calcium Exchanger; C110374:sodium-calcium exchanger 1; C054391:5-(N-4-chlorobenzyl)-N-(2',4'-dimethyl)benzamil; D000584:Amiloride