@entity1238 embryos immobilized in tubocurarine respond to natural skin stimulation with fictive swimming. This can also occur in saline without @entity1025 and is blocked by @entity143 antagonists. Ventral @entity528 which are rhythmically active during swimming are depolarized by bath applied @entity1024 ( @entity143 ) (in 1 microM @entity1022 ( @entity4524 ) to block indirect effects). By using current clamp techniques this depolarization is shown to be partially blocked by 0.5 and 1 mM @entity1025 in a voltage-dependent manner similar to that described in cultured neurons. @entity1025 partially and reversibly reduces the slow @entity143 -mediated component of excitatory post-synaptic potentials (EPSPs) in ventral neurons. However, in 1 mM @entity1025 fictive swimming can still be evoked by natural stimulation. The frequency of swimming is slightly lower than in nominally 0 mM @entity1025 , but the pattern of ventral root activity and synaptic drive to ventral neurons seems little affected. Fictive swimming can also be induced by applying @entity143 to spinal preparations. In 0 mM @entity1025 , such rhythmic activity is unstable and transient over a narrow @entity143 concentration range. In 0.5 mM @entity1025 , continuous rhythmic activity is induced over a wide range of @entity143 concentrations. Lower spinal preparations need higher @entity143 concentrations to induce activity. We conclude that the neurons rhythmically active in swimming have @entity143 receptor channels which show a voltage dependent block in the presence of @entity1025 . However, while @entity1025 exerts a powerful stabilizing influence on rhythmic activity induced in spinal embryos by exogenous @entity143 , its influence on 'naturally' evoked fictive swimming is less clear. The fictive swimming @entity75 and spinal cord can produce stable swimming with or without @entity1025 induced voltage dependency of the @entity143 channels.

The Influence of Magnesium Ions on the XXXX Mediated Responses of Ventral Rhythmic Neurons in the Spinal Cord of @entity1238 Embryos.

@entity1024 :: ('CHEBI:31882', 'Chemical') :: ['N-methyl-D-aspartate'] @entity1238 :: ('8355', 'Species') :: ['Xenopus'] @entity1025 :: ('CHEBI:18420', 'Chemical') :: ['Mg2+'] @entity75 :: ('MESH:D001927', 'Disease') :: ['machinery in the brain'] @entity1022 :: ('MESH:D013779', 'Chemical') :: ['tetrodotoxin'] @entity4524 :: ('CHEBI:9506', 'Chemical') :: ['TTX'] @entity143 :: ('CHEBI:6121', 'Chemical') :: ['NMDA'] @entity528 :: ('MESH:D009410', 'Disease') :: ['spinal cord neurons']
@entity143 :: (CHEBI:6121,Chemical) :: ['NMDA']
