title: Giant inhibitory miniature currents in crayfish muscle in the presence and absence of extracellular sodium and serotonin.
abstract: At opener muscles of the claw, or first walking leg of small crayfish, giant spontaneous inhibitory postsynaptic currents (gsIPSCs) were recorded. In some experiments, the rate by which they occurred could be enhanced by application of 1 mumol/l serotonin (5-HT). The largest gsIPSCs seen were at least up to ten-fold larger than normal inhibitory miniature currents. Picrotoxin (10 mumol/l) reversibly abolished the gsIPSCs. Tetrodotoxin (0.1 mumol/l) or withdrawal of Na+ from the superfusion did not abolish gsIPSCs. Decay time constants of gsIPSCs, tau(gsIPSCs), were about two-fold larger than those of nerve evoked IPSCs and of normal inhibitory miniature currents. In Na+-free superfusion tau(gsIPSCs) was larger by a factor of about 1.8 than in normal superfusion, which might be a result of inhibition of a Na+-dependent transport process for inhibitory transmitter by removal of Na+ from the incubation medium.
mesh_terms: D000818:Animals; D003400:Astacoidea; D004553:Electric Conductivity; D004594:Electrophysiology; D005110:Extracellular Space; D009132:Muscles / Q000502:physiology*; D009433:Neural Inhibition; D010477:Perfusion; D010852:Picrotoxin / Q000494:pharmacology; D011930:Reaction Time; D012701:Serotonin / Q000494:pharmacology*; D012964:Sodium / Q000494:pharmacology*
chemical_list: D010852:Picrotoxin; D012701:Serotonin; D012964:Sodium