Effects of tubocurarine and eserine on the axon-Schwann cell relationship in the squid nerve fibre.
The effects of eserine and D-tubocurarine on the axon and Schwann cell membrane potentials have been studied in the giant nerve fibre of the squid.1. The addition of eserine at concentrations of up to 10(-4)M to the external sea-water medium has no appreciable effects on either the Schwann cell electrical potential of unstimulated nerve fibres or on the resting and action potentials of the axon.2. However, eserine at a concentration of 10(-9)M prolongs the long-lasting Schwann cell hyperpolarizations which follow the conduction of impulse trains by the axon.3. Higher concentrations of eserine (10(-7), 10(-4)M) decrease and block the long-lasting effects of nerve impulse train conduction.4. D-tubocurarine at concentrations of up to 10(-5)M has no appreciable effect on the resting and action potentials of the axon.5. However, D-tubocurarine at a concentration of 10(-9)M blocks completely the hyperpolarizing effects of nerve impulse trains on the Schwann cell electrical potential.6. In addition to its blocking action, D-tubocurarine induces transient hyperpolarizations in the Schwann cells of unstimulated nerve fibres both in intact fibres and in slitted preparations.7. These findings suggest that a cholinergic system, which may be located at the axon-Schwann cell boundary, is involved in the genesis of the long-lasting Schwann cell hyperpolarization caused by the conduction of nerve impulse trains by the axon.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001369:Axons / Q000187:drug effects* / Q000502:physiology; D049832:Decapodiformes / Q000166:cytology; D004558:Electric Stimulation; D008564:Membrane Potentials / Q000187:drug effects*; D009431:Neural Conduction / Q000187:drug effects; D010830:Physostigmine / Q000008:administration & dosage / Q000494:pharmacology*; D012583:Schwann Cells / Q000187:drug effects* / Q000502:physiology; D014403:Tubocurarine / Q000008:administration & dosage / Q000494:pharmacology*
D010830:Physostigmine; D014403:Tubocurarine