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Influence of Ischemic-Simulation on the Action Potential Characteristics in Rat Atrial Fibers
Korean Circulation Journal ; : 1225-1233, 1999.
Artigo em Coreano | WPRIM | ID: wpr-104158
ABSTRACT

BACKGROUND:

To investigate the mechanisms of myocardial ischemia induced changes of electrophysiological properties, influences of various ischemic-simulated Tyrode's solutions on the changes of action potential characteristics were examined.

METHOD:

Action potential characteristics were measured during superfusion with various ischemic-simulated solutions (modified physiologic salt solution MPSS) by the method of conventional microelectrode technique in rat atrial fibers.

RESULTS:

Hypoxic-, hyperkalemic-, and mixed-MPSS decreased 'maximum diastolic potential' (MDP) and 'action potential amplitude' (APA), however, no significant changes of MDP and APA were observed by acidic- and glucose-free-MPSS. 'Maximum velocity of phase 0 depolarization' (dV/dt(max)) and 'time for 90% repolarization' (APD90) significantly decreased during hypoxic- and mixed-MPSS superfusion, and hyperkalemic-MPSS also decreased the dV/dt(max) and APD90. However, no significant changes in dV/dt(max) and APD90 were observed by acidic- and glucose-free-MPSS. The decreasing effects of dV/dt(max) and APD90 by the MPSSes were attenuated when the MPSSes were replaced with normal Tyrode's solution. DPCPX (2x10(-6)M), a purinergic antagonist, inhibited the decreasing effects of APD90 at 5, 10, and 20 min superfusion of the mixed-MPSS, and glibenclamide (10(-6)M), a K(ATP) channel blocker, inhibited those at 10 and 20 min superfusion of the mixed-MPSS. Diclofenac (10(-6)M), a cyclooxygenase inhibitor inhibited only those at 20 min superfusion of the mixed-MPSS.

CONCLUSION:

The primary factors for changing the electrophysiological characteristics during ischemic insults could be hypoxia and high-extracellular K+, and the mechanisms of the electrophysiological changes are inferred that adenosine through purinoceptors is involved initially, and followed by K(ATP) channel and prostanoids.
Assuntos

Texto completo: DisponíveL Índice: WPRIM (Pacífico Ocidental) Assunto principal: Potenciais de Ação / Adenosina / Prostaglandinas / Diclofenaco / Receptores Purinérgicos / Glibureto / Prostaglandina-Endoperóxido Sintases / Isquemia Miocárdica / Isquemia / Hipóxia Limite: Animais Idioma: Coreano Revista: Korean Circulation Journal Ano de publicação: 1999 Tipo de documento: Artigo

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Texto completo: DisponíveL Índice: WPRIM (Pacífico Ocidental) Assunto principal: Potenciais de Ação / Adenosina / Prostaglandinas / Diclofenaco / Receptores Purinérgicos / Glibureto / Prostaglandina-Endoperóxido Sintases / Isquemia Miocárdica / Isquemia / Hipóxia Limite: Animais Idioma: Coreano Revista: Korean Circulation Journal Ano de publicação: 1999 Tipo de documento: Artigo