Ranolazine inhibits an oxidative stress-induced increase in myocyte sodium and calcium loading during simulated-demand ischemia.
J Cardiovasc Pharmacol
; 51(5): 443-9, 2008 May.
Article
em En
| MEDLINE
| ID: mdl-18398379
ABSTRACT
Ranolazine inhibits the late Na current and is proposed to reduce angina by decreasing [Na]i during ischemia, thereby reducing Ca influx via Na/Ca exchange (NCX). We sought to test this hypothesis and to determine whether oxidative stress during simulated-demand ischemia activates the late Na current. We measured [Ca]i and [Na]i in rabbit ventricular myocytes by flow cytometry during metabolic inhibition (MI) with 2 mM cyanide and 0 mM glucose at 37 degrees C plus pacing (P) at 0.5 Hz (P-MI), and in P-MI + 1, 10, or 50 microM ranolazine. In the clinically relevant concentration range (1-10 microM), ranolazine decreased Na and Ca loading and the development of myocyte contracture. P-MI caused an increase in fluorescence of the oxidative radical probe CM-H2DCFDA, which was inhibited by the radical scavenger Tiron 20 mM. The NCX inhibitor KB-R7943 (10 microM) and Tiron 20 mM reduced the rise in [Ca]i during P-MI and eliminated the effect of 10 microM ranolazine on [Ca]i. These results indicate that oxidative stress increases the late Na current during MI. Inhibition of the resulting increase in Na and Ca loading and contracture seems to account for the observed antiischemia effects of ranolazine.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Piperazinas
/
Sódio
/
Cálcio
/
Isquemia Miocárdica
/
Estresse Oxidativo
/
Miócitos Cardíacos
/
Inibidores Enzimáticos
/
Acetanilidas
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Cardiovasc Pharmacol
Ano de publicação:
2008
Tipo de documento:
Article