Motor nerve terminal sprouting in formamide-treated inactive amphibian skeletal muscle

摘要: Motor axons can form sprouts from their terminal arborizations in response to partial denervation, and when exposed pharmacological blocking agents like TTX, botulinum toxins alpha-bungarotoxin, or curare. Each of these experimental procedures has cessation muscle contractile activity as a common feature. We tested the specific role fiber inactivity regulating nerve sprouting by chronically treating adult frog (Rana pipiens) cutaneous pectoris muscles with formamide. Exposure formamide, unlike other compounds used study sprouting, selectively inhibits contractions without pre- postsynaptic transmission action potentials. Repeated formamide applications were achieve chronic block vivo for up 6 weeks. formamide-treated inactive sprouted only arborizations, but not nodes Ranvier. The onset this was protracted compared that seen pharmacologically blocked mammalian muscles, more complex ornate. frequency terminals less than after alternate methods block, suggests alone serves moderate cue sprouting. possibility is discussed prolific following neurotoxin administration may, fact, be due perturbations synaptic electrical rather inactivity.