Analysis of frog neuromuscular function at hyperbaric pressures

Nerve and muscle compound action potentials were measured in the frog sciatic nerve-gastrocnemius muscle preparation in a hyperbaric helium-air environment. Helium pressure to 69 ATA induced a reversible depression in muscle compound action potential amplitude without significantly affecting other parameters. Blockade other parameters. Blockade induced by tetraethylammonium while at pressure could be partially reversed by decompression. A desensitization-type of neuromuscular block produced at pressure after neostigmine infusion could also be partially reversed by decompression. These results suggest a possible involvement of the acetylcholine receptor complex in pressure-induced depression of synaptic transmission.