Trifluoperazine: a rynodine receptor agonist.
Pflugers Arch
; 458(4): 643-51, 2009 Aug.
Article
en En
| MEDLINE
| ID: mdl-19277699
Trifluoperazine (TFP), a phenothiazine, is a commonly used antipsychotic drug whose therapeutic effects are attributed to its central anti-adrenergic and anti-dopaminergic actions. However, TFP is also a calmodulin (CaM) antagonist and alters the Ca(2+) binding properties of calsequestrin (CSQ). The CaM and CSQ proteins are known modulators of sarcoplasmic reticulum (SR) Ca(2+) release in ventricular myocytes. We explored TFP actions on cardiac SR Ca(2+) release in cells and single type-2 ryanodine receptor (RyR2) channel activity in bilayers. In intact and permeabilized ventricular myocytes, TFP produced an initial activation of RyR2-mediated SR Ca(2+) release and over time depleted SR Ca(2+) content. At the single channel level, TFP or nortryptiline (NRT; a tricyclic antidepressant also known to modify CSQ Ca(2+) binding) increased the open probability (Po) of CSQ-free channels with an EC(50) of 5.2 microM or 8.9 microM (respectively). This Po increase was due to elevated open event frequency at low drug concentrations while longer mean open events sustained Po at higher drug concentrations. Activation of RyR2 by TFP occurred in the presence or absence of CaM. TFP may also inhibit SR Ca uptake as well as increase RyR2 opening. Our results suggest TFP and NRT can alter RyR2 function by interacting with the channel protein directly, independent of its actions on CSQ or CaM. This direct action may contribute to the clinical adverse cardiac side effects associated with these drugs.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Trifluoperazina
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Agonistas de los Canales de Calcio
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Función Ventricular Izquierda
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Canal Liberador de Calcio Receptor de Rianodina
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Señalización del Calcio
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Miocitos Cardíacos
Límite:
Animals
Idioma:
En
Revista:
Pflugers Arch
Año:
2009
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Alemania