Formation of a border ischemic zone depends on plasma potassium concentration.
Can J Physiol Pharmacol
; 102(5): 331-341, 2024 May 01.
Article
em En
| MEDLINE
| ID: mdl-38118123
ABSTRACT
Extracellular potassium concentration might modify electrophysiological properties in the border zone of ischemic myocardium. We evaluated the depolarization and repolarization characteristics across the ischemic-normal border under [K+] variation. Sixty-four-lead epicardial mapping was performed in 26 rats ([K+] 2.3-6.4 mM) in a model of acute ischemia/reperfusion. The animals with [K+] < 4.7 mM (low-normal potassium) had an ischemic zone with ST-segment elevation and activation delay, a border zone with ST-segment elevation and no activation delay, and a normal zone without electrophysiological abnormalities. The animals with [K+] >4.7 mM (normal-high potassium) had only the ischemic and normal zones and no transitional area. Activation-repolarization intervals and local conduction velocities were inversely associated with [K+] in linear regression analysis with adjustment for the zone of myocardium. The reperfusion extrasystolic burden (ESB) was greater in the low-normal as compared to normal-high potassium animals. Ventricular tachycardia/fibrillation incidence did not differ between the groups. In patch-clamp experiments, hypoxia shortened action potential duration at 5.4 mM but not at 1.3 mM of [K+]. IK(ATP) current was lower at 1.3 mM than at 5.4 mM of [K+]. We conclude that the border zone formation in low-normal [K+] was associated with attenuation of IK(ATP) response to hypoxia and increased reperfusion ESB.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Potássio
/
Potenciais de Ação
/
Isquemia Miocárdica
Limite:
Animals
Idioma:
En
Revista:
Can J Physiol Pharmacol
Ano de publicação:
2024
Tipo de documento:
Article
País de afiliação:
Federação Russa