Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Improvement of diaphragm and limb muscle isotonic contractile performance by K+ channel blockade | van Lunteren and Pollarine Journal of NeuroEngineering and Rehabilitation 2010 7 1 http content 7 1 1 JNER JOURNAL OF NEUROENGINEERING AND REHABILITATION RESEARCH Open Access Improvement of diaphragm and limb muscle isotonic contractile performance by K channel blockade Erik van Lunteren Jennifer Pollarine Abstract The K channel blocking aminopyridines greatly improve skeletal muscle isometric contractile performance during low to intermediate stimulation frequencies making them potentially useful as inotropic agents for functional neuromuscular stimulation applications. Most restorative applications involve muscle shortening however previous studies on the effects of aminopyridines have involved muscle being held at constant length. Isotonic contractions differ substantially from isometric contractions at a cellular level with regards to factors such as cross-bridge formation and energetic requirements. The present study tested effects of 3 4-diaminopyridine DAP on isotonic contractile performance of diaphragm extensor digitorum longus EDL and soleus muscles from rats. During contractions elicited during 20 Hz stimulation DAP improved work over a range of loads for all three muscles. In contrast peak power was augmented for the diaphragm and EDL but not the soleus. Maintenance of increased work and peak power was tested during repetitive fatigue-inducing stimulation using a single load of 40 and a stimulation frequency of 20 Hz. Work and peak power of both diaphragm and EDL were augmented by DAP for considerable periods of time whereas that of soleus muscle was not affected significantly. These results demonstrate that DAP greatly improves both work and peak power of the diaphragm and EDL muscle during isotonic contractions which combined with previous data on isometric contractions indicates that this agent is suitable for enhancing muscle performance during a range of contractile modalities. Background The aminopyridines are a group of .
