Koller M L, Riccio M L, Gilmour R F
Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853-6401, USA.
Am J Physiol Heart Circ Physiol. 2000 Dec;279(6):H2665-72. doi: 10.1152/ajpheart.2000.279.6.H2665.
To test whether hyperkalemia suppresses ventricular fibrillation (VF) by reducing the slope of the action potential duration (APD) restitution relation, we determined the effects of the extracellular K(+) concentration (K(+)) ([KCl] = 2.7-12 mM) on the restitution of APD and maximum upstroke velocity (V(max)) the magnitude of APD alternans and spatiotemporal organization during VF in isolated canine ventricle. As [KCl] was increased incrementally from 2.7 to 12 mM, V(max) was reduced progressively. Increasing [KCl] from 2.7 to 10 mM decreased the slope of the APD restitution relation at long, but not short, diastolic intervals (DI), decreased the range of DI over which the slope was >/=1, and reduced the maximum amplitude of APD alternans. At [KCl] = 12 mM, the range of DI over which the APD restitution slope was >/=1 increased, and the maximum amplitude of APD alternans increased. For [KCl] = 4-8 mM, the persistence of APD alternans at short DI was associated with maintenance of VF. For [KCl] = 10-12 mM, the spontaneous frequency during VF was reduced, and activation occurred predominantly at longer DI. The lack of APD alternans at longer DI was associated with conversion of VF to a periodic rhythm. These results provide additional evidence for the importance of APD restitution kinetics in the development of VF.
为了测试高钾血症是否通过降低动作电位时程（APD）恢复关系的斜率来抑制心室颤动（VF），我们测定了细胞外钾离子浓度（[K⁺]ₒ）（[KCl] = 2.7 - 12 mM）对离体犬心室中APD恢复、最大上升速度（Vₘₐₓ）、APD交替变化幅度以及VF期间时空组织的影响。随着[KCl]从2.7 mM逐渐增加到12 mM，Vₘₐₓ逐渐降低。将[KCl]从2.7 mM增加到10 mM会降低长舒张期（DI）而非短舒张期时APD恢复关系的斜率，减小斜率≥1时的DI范围，并降低APD交替变化的最大幅度。当[KCl] = 12 mM时，APD恢复斜率≥1的DI范围增加，且APD交替变化的最大幅度增加。对于[KCl] = 4 - 8 mM，短DI时APD交替变化的持续存在与VF的维持有关。对于[KCl] = 10 - 12 mM，VF期间的自发频率降低，激活主要发生在较长的DI时。较长DI时缺乏APD交替变化与VF转变为周期性节律有关。这些结果为APD恢复动力学在VF发生中的重要性提供了额外证据。
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