van Lunteren Erik, Pollarine Jennifer, Moyer Michelle
Cleveland Department of Veterans Affairs Medical Center, Cleveland OH, USA.
IEEE Trans Neural Syst Rehabil Eng. 2006 Dec;14(4):419-26. doi: 10.1109/tnsre.2006.886729.
The K+ channel blocker 3,4-diaminopyrindine (DAP) increases diaphragm force, use of which could potentially improve muscle performance during functional neuromuscular stimulation. To determine the extent of hindlimb muscle force augmentation, and delineate whether DAP effects vary in muscles comprised of mainly slow versus fast fibers, rat soleus, extensor digitorum longus (EDL) and diaphragm muscle samples were studied in vitro. DAP increased force of all three muscles, but at high concentrations the force increases were transient and were followed by declines in force below baseline. The maximum DAP-induced twitch force increase was smaller for soleus (38 +/-7%) than both EDL (94+/-12%) (P < 0.05) and diaphragm (93+/-13%) (P < 0.01). During fatigue-inducing 20 Hz stimulation (tested at an intermediate DAP concentration), force of soleus muscle remained significantly elevated by DAP for the entire testing period, force of DAP-treated EDL muscle rapidly declined to values in untreated muscle, and force of DAP-treated diaphragm had an intermediate force-time profile. Muscles varied in extent to which isometric contractile kinetics were altered by DAP. Thus, the K+ channel blocker DAP improves contractile performance of limb muscles, but the profile of improvement is distinct between the soleus and EDL muscles.
钾离子通道阻滞剂3,4 - 二氨基吡啶（DAP）可增强膈肌力量，在功能性神经肌肉刺激过程中使用它可能会改善肌肉性能。为了确定后肢肌肉力量增强的程度，并描绘DAP的作用在主要由慢肌纤维与快肌纤维组成的肌肉中是否存在差异，对大鼠的比目鱼肌、趾长伸肌（EDL）和膈肌样本进行了体外研究。DAP增加了所有这三块肌肉的力量，但在高浓度时，力量增加是短暂的，随后力量会降至基线以下。DAP诱导的比目鱼肌最大抽搐力量增加幅度（38±7%）小于趾长伸肌（94±12%）（P < 0.05）和膈肌（93±13%）（P < 0.01）。在诱发疲劳的20Hz刺激期间（在中等DAP浓度下进行测试），整个测试期间，DAP使比目鱼肌的力量显著升高，DAP处理的趾长伸肌的力量迅速下降至未处理肌肉的水平，而DAP处理的膈肌的力量 - 时间曲线处于中间状态。不同肌肉因DAP改变等长收缩动力学的程度有所不同。因此，钾离子通道阻滞剂DAP可改善肢体肌肉的收缩性能，但比目鱼肌和趾长伸肌之间的改善情况有所不同。
