Sherman M S, Aldrich T K, Chaudhry I, Nagashima H
Department of Medicine and Anesthesiology, North Central Bronx Hospital.
Am Rev Respir Dis. 1988 Nov;138(5):1180-4. doi: 10.1164/ajrccm/138.5.1180.
Digoxin could improve diaphragm contractility and fatigability if inhibition of sodium-potassium adenosine triphosphatase enhances calcium influx from extracellular sources, or it could impair contractility and worsen fatigue if it impairs maintenance of the membrane potential. We studied the effects of digoxin on isometric force production, fatigue, and recovery in isolated, directly stimulated, guinea pig and rat diaphragms. Digoxin had no effect on maximal twitch or tetanic tensions compared with control diaphragms in either rat (2 ng/ml to 20 micrograms/ml) or guinea pig (2 ng/ml to 2 micrograms/ml) hemidiaphragms. Digoxin worsened high frequency fatigue and impaired recovery from fatigue in guinea pigs (200 ng/ml to 2 micrograms/ml) but not in rat (2 micrograms/ml) hemidiaphragms. We conclude that digoxin has no effect on diaphragm contractility. Hypopolarization of the membrane potential is the likely cause for the increased fatigability. The difference in responsiveness between species is likely due to insensitivity of rat sodium-potassium adenosine triphosphatase to digoxin.
如果抑制钠钾三磷酸腺苷酶能增强细胞外钙内流，地高辛可改善膈肌收缩力和疲劳性；但如果它损害膜电位的维持，则可能损害收缩力并加重疲劳。我们研究了地高辛对分离的、直接刺激的豚鼠和大鼠膈肌等长力产生、疲劳及恢复的影响。在大鼠（2纳克/毫升至20微克/毫升）或豚鼠（2纳克/毫升至2微克/毫升）半膈肌中，与对照膈肌相比，地高辛对最大抽搐或强直张力无影响。地高辛使豚鼠（200纳克/毫升至2微克/毫升）高频疲劳加重且损害疲劳恢复，但对大鼠（2微克/毫升）半膈肌无此影响。我们得出结论，地高辛对膈肌收缩力无影响。膜电位的去极化可能是疲劳性增加的原因。物种间反应性的差异可能是由于大鼠钠钾三磷酸腺苷酶对地高辛不敏感。
