Graded and decremental response in heart muscle fibers.
Graded and decremental response in heart muscle fibers.
复制标题
心肌纤维的分级和递减反应。
DOI：
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发表时间：
1958
影响因子：
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通讯作者：
B. Hoffman
中科院分区：
文献类型：
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作者：
C. Y. Kao;B. Hoffman
同时记录的跨膜电位从两个点在一个单一的心脏纤维表明，在不应期复极约一半时，完整的分级反应出现接近刺激的网站。对阴极脉冲的这些响应在幅度上随刺激强度而变化，并且即使在刺激电极附近存在过冲时也可以显示空间递减。结果表明，从分级到全或无反应的过渡并不仅仅取决于膜电位的恢复。在一些实验中，刺激是通过采用一个管腔的双微电极完成的;在其他单浦肯野纤维刺激的动作电位从附着的乳头肌传播。在这两种情况下都得到了类似的分级反应。采用传播动作电位作为刺激的实验表明，在完整的心脏中可能发生分级活动作为反应机制。
Simultaneous records of the transmembrane potential from two points in a single cardiac fiber indicate that during the refractory period when repolarization is about half complete graded responses appear close to the site of stimulation. These responses to cathodal pulses vary in amplitude with stimulus intensity and may show spatial decrement even when an overshoot is present close to the stimulating electrode. The results obtained indicate that the transition from graded to all-or-none response does not depend solely on the restoration of membrane potential. In some experiments stimulation was accomplished by employing one lumen of a double microelectrode; in others single Purkinje fibers were stimulated by action potentials propagated from attached papillary muscle. Similar graded responses were elicited in both instances. The experiments employing propagating action potentials as stimuli suggest the possible occurrence of graded activity as a response mechanism in the intact heart.