Mitochondrial Na+/Ca2+-exchanger blocker CGP37157 protects against chromaffin cell death elicited by veratridine.
Mitochondrial calcium (Ca(2+)) dyshomeostasis constitutes a critical step in the metabolic crossroads leading to cell death. Therefore, we have studied here whether 7-chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one (CGP37157; CGP), a blocker of the mitochondrial Na(+)/Ca(2+)-exchanger (mNCX), protects against veratridine-elicited chromaffin cell death, a model suitable to study cell death associated with Ca(2+) overload. Veratridine produced a concentration-dependent cell death, measured as lactate dehydrogenase released into the medium after a 24-h incubation period. CGP rescued cells from veratridine-elicited death in a concentration-dependent manner; its EC(50) was approximately 10 microM, and 20 to 30 microM caused near 100% cytoprotection. If preincubated for 30 min and washed out for 3 min before adding veratridine, CGP still afforded significant cytoprotection. At 30 microM, CGP blocked the veratridine-elicited free radical production, mitochondrial depolarization, and cytochrome c release. At this concentration, CGP also inhibited the Na(+) and Ca(2+) currents by 50 to 60% and the veratridine-elicited oscillations of cytosolic Ca(2+). This drastic cytoprotective effect of CGP could be explained in part through its regulatory actions on the mNCX.
Nicolau
Santos M
SM
Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, C/Arzobispo Morcillo, 4, 28029-Madrid, Spain.
de Diego
Antonio M G
AM
Cortés
Lorena
L
Egea
Javier
J
González
José C
JC
Mosquera
Marta
M
López
Manuela G
MG
Hernández-Guijo
Jesús Miguel
JM
García
Antonio G
AG
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D002417:Cattle; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000187:drug effects* / Q000201:enzymology; D002998:Clonazepam / Q000031:analogs & derivatives* / Q000494:pharmacology; D004396:Coloring Agents; D045304:Cytochromes c / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D017382:Reactive Oxygen Species; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors*; D013778:Tetrazolium Salts; D013841:Thiazepines / Q000494:pharmacology*; D013844:Thiazoles; D014701:Veratridine / Q000037:antagonists & inhibitors* / Q000633:toxicity*
D015220:Calcium Channels; D004396:Coloring Agents; D017382:Reactive Oxygen Species; D015222:Sodium Channels; D019831:Sodium-Calcium Exchanger; D013778:Tetrazolium Salts; D013841:Thiazepines; D013844:Thiazoles; D002998:Clonazepam; D014701:Veratridine; C079032:CGP 37157; D045304:Cytochromes c; D007770:L-Lactate Dehydrogenase; C022616:thiazolyl blue