Groups of embryonic (I suppose) myocytes normally start to contract by themselfs. Since motoneurons can be stimulated by neurotransmitters you have several options See Mai Paxinos Human nervous system voor type of effective neurotransmitters.
Important are: duration of your culture/bath, outgrowth of axons is normally between 3 till 7 days.
I am using a co-culture of ES cell-derived MNs with differntiated Adult Skeletal Muscle cells. The age of the co-culture is 8 days,;I can see sporadic contraction of the myotubules, but the frequency of contraction is quite low. This is why I would like to stimuate contraction by activating the MNs. The outgrowth of axons is fairly high!!
Finally, I have found a paper by James Hickman lab (see below), where they use 50 mM Glut for activating MNs and stimulate contraction of underlying myotubules. Let's see how does it go!
Cheers,
Josema
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