title: 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.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D003058:Cockroaches / Q000502:physiology; D007473:Ion Channels / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects*; D008121:Nephropidae / Q000502:physiology*; D009469:Neuromuscular Junction / Q000187:drug effects*; D009479:Neuropeptides; D018377:Neurotransmitter Agents / Q000502:physiology; D009842:Oligopeptides / Q000494:pharmacology* / Q000502:physiology; D013268:Stimulation, Chemical; D009435:Synaptic Transmission
chemical_list: D007473:Ion Channels; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009842:Oligopeptides; C011536:proctolin; D002118:Calcium