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G T Bruggencate

Publications and source records attributed to G T Bruggencate.

7 recordsLinked to original sources
PubMed1977

Calcium modulation in brain extracellular microenvironment demonstrated with ion-selective micropipette.

Changes in extracellular Ca2+ concentration were directly measured in the rat cerebellum, using an ion-selective micropipette. Extracellular K+ was measured simultaneously with a second ion-selective micropipette. The potential reference barrels of the ion electrodes also provided fast field and slow potentials. During repetitive stimulation of the parallel fiber--Purkinje cell cerebellar circuit, extracellular Ca2+ fell to about 80% of base line concentration. During the spreading depression of Leão, extracellular Ca2+ fell to about 10% of base line; decreases of this magnitude also occurred during terminal anoxia. In all cases extracellular K+ increased substantially. These results show that extracellular Ca2+ is modulated during neuronal activity in the central nervous system and that under some conditions the Ca2+ change can be extreme. Given the well-established and antagonistic effects of reduce extracellular Ca2+ on axonal excitability and synaptic transmission, these results suggest that Ca2+ modulation in the brain cell microenvironment may be a significant parameter in the behavior of neuronal ensembles.

Animals↗
PubMed1976

Climbing fiber evoked potassium release in cat cerebellum.

K+-selective micropipettes were used to measure the extracellular K+-signal associated with the activation of a single Purkinje cell, via a climbing fiber (CF). The maximum K+-signal had a magnitude of 0.3 - 0.5 mM and was correlated with a positive all-or-none extracellular potential. The ionic signal was of the same order of magnitude as that evoked from a population of Purkinje cells by local stimulation of a parallel fiber beam. The large size of the CF-evoked K+-response supports the concept of dendritic spikes under these conditions and may be relevant to CF function.

Animals↗