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Biomedical subjects

D L Gilbert

Publications and source records attributed to D L Gilbert.

At least 73 records · Page 4Linked to original sources
PubMed1978

Effects of yohimbine on squid axons.

Yohimbine, an indolealkylamine alkaloid, reduces the amplitude of the sodium current in the squid giant axon. For doses that reduce sodium current amplitude by up to 50%, there is no significant change in the kinetics or in any of the voltage-dependent parameters associated with sodium channels. The effective equilibrium constant for yohimbine binding to the sodium channel is 3 x 10(-4) M. Repetitive depolarizing pulses increase the inhibition of squid axon sodium current by yohimbine. This use-dependent inhibition is enhanced by increasing the concentration of yohimbine, by increasing the frequency of pulsing, and by increasing the magnitude or the duration of depolarization. It is reduced by hyperpolarizing prepulses. This behavior can be explained by a model wherein yohimbine binds more readily to open sodium channels than to closed sodium channels and wherein the Hodgkin-Huxley kinetic parameters are modified by the binding of the drug. This type of model may also explain the tonic and use-dependent inhibition previously described by others for local anesthetics.

Action Potentials↗
PubMed1977

Helium pressure alteration of function in squid giant synapse.

The squid giant synapse, which permits intracellular electrical measurements in a single, excitatory synapse, was exposed to helium pressures up to 204 atm. By stimulating presynaptically and recording postsynaptically with an intracellular electrode it was found that pressure alters, but does not prevent, synaptic transmission of action potentials. Synaptically transmitted action potentials are prolonged in the same way as in the directly stimulated axon. However, slowing of the excitatory postsynaptic potential and marked increases in synaptic fatigue were observed at pressures as low as 35 atm. These changes may contribute to high pressure nervous effects by interfering with information transfer within the nervous system.

Action Potentials↗
PubMed1972

Diphenylhydantoin inhibition of sodium conductance in squid giant axon.

Diphenylhydantoin, in concentration of 5-50 muM, decreases the early, transient (sodium) currents of voltage-clamped squid giant axons. These effects are dose-dependent and largely reversible. It appears that diphenylhydantoin reduces the number of open, early, transient (sodium) channels.

Animals↗