The observation of spontaneous ionic currents in sea urchin protractor muscle

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Schieber, Marq
Besh, Jordan
Sheley, Christopher
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Scholarship Sewanee 2020 , Electrophysiology , Neurobiology , Echinoids , Muscle , Sea urchins , Lantern protractor muscle
Sea urchins utilize a complex set of masticatory muscles that surround a centralized structure called the Aristotle’s lantern. The muscles that surround the pentaradial lantern include paired and unpaired muscle groups. One muscle in particular is the lantern protractor muscle. What remains unknown are the type of ionic currents involved in maintaining the membrane potential of protractor muscle cells that controls contraction. Individual protractor cells were isolated from muscle segments in the purple sea urchin (Strongylocentrotus purpuratus), and the ionic currents passing through the membranes of these cells were measured using whole cell patch clamp electrophysiology. A reduced potassium solution was utilized in a perfusion system to measure differences in ionic current between control sea water and reduced potassium sea water. Changes in membrane currents were observed in both extracellular conditions. The resulting electrical events recorded from these current changes were indicative of ion channel functioning on the muscle membrane in response to differing extracellular solutions. Quantitative analysis of the frequency, amplitude, and area of these events will determine the effect of potassium in the generation of the spontaneous currents observed in protractor muscle contraction. The present study forms the basis for further electrophysiological investigation into the lantern protractor muscle. Future studies should look to incorporate a calcium reduced ion solution in the perfusion system to see whether there are calcium-activated or calcium permeable channels in the protractor muscle cell membrane.