Effect of Electrical Stimulation on Grasshopper Jumping Muscle

Abstract

Skeletal muscles can undergo biochemical and physiological changes due to exercise training. For example, aerobic exercise training may lead to an increased mitochondria volume, a higher proportion of slow twitch myosin ATPase, and a reduced rate of lactic acid production. Similar changes in mammalian muscle have also been demonstrated using electrical stimulation. However, it is unclear if invertebrate muscle also responds to training or electrical stimulation. We examine whether Schistocerca americana grasshopper jumping muscles are affected by electrical stimulation. Grasshopper jumping muscle is one of the few invertebrate muscles to produce lactic acid during locomotion. Electrical probe leads are placed near the coxa on the ventral side of the animal. The muscle was stimulated with a single pulse width of 2 ms at 0.075 V and repeated at a frequency of 100 Hz. We electrically stimulate the entire jumping muscle, including both the flexor and the extensor, to elicit continuous muscle contractions in a single metathoracic leg. To invoke a training response, a grasshopper is stimulated for 5 hours daily for 5 consecutive days. The lactate production rate of trained and untrained grasshopper muscle will then be fluorometrically measured after 5 min, 30 min, 60 min, 180 min, or 300 min of electrical stimulation. We predict that repeated stimulation would alter the rate of lactic acid production. Since grasshopper jumping muscle is similar to human muscle, this research may provide insight into fundamental questions about muscle plasticity.Support or Funding InformationUnion College Undergraduate Research Committee