Block of conduction in partially depolarized cardiac purkinje fibres induced by an -adrenergic agent.
Block of conduction in partially depolarized cardiac purkinje fibres induced by an -adrenergic agent.
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由β-肾上腺素能药物引起的部分去极化心脏浦肯野纤维的传导阻滞。
DOI：
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发表时间：
1971
期刊：
影响因子：
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通讯作者：
A. L. Wit
中科院分区：
文献类型：
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作者：
P. Cranefield;B. Hoffman;A. L. Wit
如果心室传导系统的离散区域暴露于高浓度的K+，则通过这些区域的传导减慢得如此之多，以致于脉冲可能在不应期结束后重新进入传导系统的正常部分，从而引起心脏的另一次兴奋（参考文献10）。1和2以及我们未发表的工作）。这种缓慢的传导是由一种缓慢的反应引起的，这种反应类似于心脏动作电位的缓慢成分3和房室结正常纤维的动作电位4。肾上腺素增强浦肯野纤维的反应，暴露于高K+浓度5会抑制浦肯野纤维的反应，我们现在报告α-肾上腺素能药物甲氧胺在不影响正常动作电位的浓度下抑制缓慢反应。这一发现很有意义，因为肾上腺素能药物对心脏的作用很少可归因于α受体的刺激6，因为选择性抑制慢反应进一步证明了它与正常纤维的反应在性质上不同（我们未发表的工作），还因为它表明α肾上腺素能药物可能有助于预防某些心律失常。
IF discrete areas of the ventricular conducting system are exposed to high concentrations of K+, conduction through these areas is slowed so much that the impulse may re-enter the normal part of the conducting system after the end of the refractory period, thereby evoking another excitation of the heart (refs. 1 and 2 and our unpublished work). This slow conduction results from a slow response that resembles the slow component of the cardiac action potential3 and the action potential of normal fibres of the atrioventricular node4. Adrenaline enhances the response of Purkinje fibres, depressed by exposure to high K+ concentration5 and we now report that an α-adrenergic agent, methoxamine, depresses the slow response at concentrations that do not affect the normal action potential. This finding is of interest because very few of the actions of adrenergic agents on the heart can be attributed to the stimulation of α-receptors6, because selective depression of the slow response is further evidence that it differs qualitatively from the response of normal fibres (our unpublished work) and because it suggests that α-adrenergic agents may be useful in the prevention of certain cardiac arrhythmias.