A slow EPSP in mammalian inferior mesenteric ganglion persists after in vivo capsaicin.
The non-cholinergic slow excitatory postsynaptic potential (EPSP) in the guinea pig inferior mesenteric ganglion (IMG) is believed to be mediated by substance P (SP). Yet, in ganglia of guinea pigs treated with capsaicin (50, 100, or 350 mg/kg, s.c.), a compound that depletes SP from sensory neurons, slow EPSPs were only 50% smaller in amplitude than those in vehicle-treated controls; this was true at all dosages. When ganglia from capsaicin-treated animals were desensitized to SP, slow EPSP amplitude was decreased by 50% from predesensitization values. These data indicate that capsaicin does not eliminate the slow EPSP in the IMG and suggest that both SP and another transmitter are involved in co-mediating this response.
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000032:analysis; D005728:Ganglia, Sympathetic / Q000502:physiology*; D006168:Guinea Pigs; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009475:Neurons, Afferent / Q000032:analysis; D013373:Substance P / Q000032:analysis / Q000502:physiology*; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects
D013373:Substance P; D002211:Capsaicin