Multiple reversal potentials for responses to L-glutamic acid.

Reversal potentials for L-glutamic and kainic acid were determined from foetal mouse neurones, grown dissociated in culture, and originating either from the brain or spinal cord. Amino acids were applied at known concentrations by pressure microperfusion and responses recorded using conventional intracellular techniques. Altering membranes potential by injecting current through the recording electrode permitted direct (not extrapolated) observation of reversal potentials.

Two conductance mechanisms activated by applications of L-glutamic, L-aspartic, DL-homocysteic, N-methyl-D-aspartic, and DL-kainic acids to cultured mammalian central neurones.

Neurones of foetal mouse spinal cord or brain were grown dissociated in tissue culture. Intracellular recordings from single neurones demonstrated two types of conductance changes in response to applications of L-glutamic acid and a number of structurally related compounds. In the presence of 10 mM MgCl2 the responses consisted of an increase in membrane conductance.

The effects of pentobarbital and related compounds on frog motoneurons.

The effect of pentobarbital (PB) and related compounds on frog motoneurons was examined with sucrose gap recording from the ventral roots. PB was found to: (1) depress the action of glutamate, (2) selectively enhance the action of GABA, (3) reverse the non-competitive picrotoxin antagonism of GABA and the competitive strychnine antagonism of beta-alanine, but not the competitive bicuculline methiodide antagonism of GABA, and (4) elicit a GABAmimetic hyperpolarization. The first three actions had a threshold concentration of 10 microM, while the GABAmimetic action required a 10-fold higher concentration.

Computed tomography in preoperative diagnosis of conjoined twins.

A case of thoracoomphalopagus twins diagnosed preoperatively by computed tomography is described.