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Updated: Aug 19, 2026

Historical View and Physiology Demonstration at the NMJ of the Crayfish Opener Muscle
Published on: November 10, 2009
A peptide action in a lobster neuromuscular preparation
Abstract:
The neuropeptide proctolin causes a sustained contraction of the opener muscle of the dactyl of the lobster walking leg. This substance acts directly on the muscle at concentrations as low as 10(-10)M. The contraction is dependent on extracellular calcium. Neither a significant depolarization nor a detectable change in the input resistance accompanies the response. No presynaptic action of proctolin is indicated; excitatory and inhibitory junctional potential sizes and the frequency of spontaneous miniature excitatory junctional potentials are unaffected.
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