title: Muscle paralyzing effect of the juice from the trunk of the banana tree.
abstract: The effect of an extract from the trunk of the banana tree (Musa sapientum) was investigated in isolated skeletal muscle preparations from the chick, mouse and frog using twitch tension and intracellular recording techniques. The extract produced, in the same concentration range and after an initial period of twitch augmentation, paralysis of skeletal muscle in both directly and indirectly stimulated preparations. It also had a dose-dependent stimulant effect on the muscle causing a contracture. The neuromuscular blockade was reversed by calcium, but only when added before complete paralysis of the muscle. On the other hand, neostigmine usually hastened the blockade and aggravated the contracture. The frequency of the miniature endplate potential in the mouse phrenic nerve-diaphragm preparation greatly increased initially, declining to an elevated plateau. Effects on quantal content of endplate potentials (e.p.p.s) were studied in the transected mouse phrenic nerve-hemidiaphragm using trains of e.p.p.s. In the presence of the extract, only a few e.p.p. trains could normally be evoked, probably due to nerve terminal block. When quantal content could be measured at low concentrations of the extract, an increase was usually obtained. Muscle action potentials in the frog sartorius muscle were decreased in amplitude until no further potentials could be generated. The results suggest that the nature of the block produced by the extract resembles that of a potent local anaesthetic with an initial atypical labilizing effect on cell calcium rather than a conventional curariform block.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002645:Chickens; D003964:Diaphragm / Q000187:drug effects; D066298:In Vitro Techniques; D051379:Mice; D009045:Motor Endplate / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects*; D009388:Neostigmine / Q000494:pharmacology; D010791:Phrenic Nerve / Q000187:drug effects; D010936:Plant Extracts / Q000633:toxicity*; D011189:Potassium Chloride / Q000494:pharmacology; D011894:Rana pipiens; D009435:Synaptic Transmission / Q000187:drug effects; D013997:Time Factors
chemical_list: D010936:Plant Extracts; D009388:Neostigmine; D011189:Potassium Chloride