Octopamine action on the spontaneous contractions of the isolated nerve cord of Lumbricus terrestris.
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.
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
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D009655:Octopamine; D013779:Tetrodotoxin; C028435:2-octopamine; D013578:Synephrine