title: Octopamine action on the spontaneous contractions of the isolated nerve cord of Lumbricus terrestris.
abstract: Octopamine and synephrine were observed to effect the spontaneous rhythmic contractions displayed by the isolated ventral nerve cord of the earthworm, Lumbricus terrestris. octopamine and synephrine produced dose-dependent significant changes in the frequency, amplitude and basal tonus of the spontaneous contractions. Application of adrenergic receptor antagonists suggested the octopamine receptors to have some similarity to vertebrate alpha 1-adrenergic receptors. The spontaneous contractions were not abolished by tetrodotoxin (TTX) which suggested a myogenic origin for the contraction of the ventral nerve cord sheath muscles. Octopamine, in the presence of TTX, increased the basal tonus and maximum force of the spontaneous contractions.
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D009119:Muscle Contraction / Q000187:drug effects; D009420:Nervous System / Q000187:drug effects; D009424:Nervous System Physiological Phenomena; D009655:Octopamine / Q000494:pharmacology*; D009835:Oligochaeta / Q000502:physiology*; D013578:Synephrine / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D009655:Octopamine; D013779:Tetrodotoxin; C028435:2-octopamine; D013578:Synephrine