Development of action potential in larval muscle fibers in Drosophila melanogaster

In the presence of tetraethylammonium or barium ions, the larval muscle fibers of Drosophila melanogaster were found to produce an all-or-none action potential operated by the calcium channels. The development of this distinctive membrane property during the maturation of muscle cells was studied by measuring the maximum rate of rise of the action potential in the larval muscle fibers at different stages of development from the sixteenth to ninety-sixth hours after hatching. The value increased significantly with age until a peak was reached at the sixty-fourth hour, although it became lower again as puparium formation neared at about the ninety-sixth hour. This suggests that during larval development the muscle fibers develop the ability to generate an action potential due to an inward current through the calcium channels, although the ability became lower at the later stage of larval development.