1. We have investigated changes in extracellular potassium concentration [K+]o in the supraoptic ... more 1. We have investigated changes in extracellular potassium concentration [K+]o in the supraoptic nucleus of lactating rats and in particular those that occur during the intense burst of firing by the oxytocin neurones involved in the milk ejection reflex. 2. Double-barrelled K(+)-selective microelectrodes containing a highly selective sensor based on valinomycin were lowered through the exposed cortex towards the supraoptic nucleus (SON) of female rats anaesthetized with urethane. The mean resting [K+]o in the hypothalami of five rats was 2.4 mM, S.D. = 0.3 mM. 3. Where the reference barrel recorded extracellular action potentials from an oxytocin cell, the reflex burst of firing (4 s, typical maximum 50 Hz) was accompanied by a mean increase in [K+]o (delta[K+]o) of 0.22 mM (S.E.M. = 0.02 mM, fifty-seven bursts in eight cells in seven rats). The rise in [K+]o did not begin more than 0.1 s before the onset of the burst, and began to fall from its maximum during the burst. Slow field...
... Permissions & Reprints. III. Glia-neuronal signaling Chapter 12. Metabolic trafficking be... more ... Permissions & Reprints. III. Glia-neuronal signaling Chapter 12. Metabolic trafficking between cells in nervous tissue. Jonathan A. Coles Corresponding Author Contact Information , 1 , E-mail The Corresponding Author , Céline Véga 2 , ** and Païkan Marcaggi 2 , ***. ...
There is significant evidence that brain-infiltrating CD8+ T cells play a central role in the dev... more There is significant evidence that brain-infiltrating CD8+ T cells play a central role in the development of experimental cerebral malaria (ECM) during Plasmodium berghei ANKA infection of C57BL/6 mice. However, the mechanisms through which they mediate their pathogenic activity during malaria infection remain poorly understood. Utilizing intravital two-photon microscopy combined with detailed ex vivo flow cytometric analysis, we show that brain-infiltrating T cells accumulate within the perivascular spaces of brains of mice infected with both ECM-inducing (P. berghei ANKA) and non-inducing (P. berghei NK65) infections. However, perivascular T cells displayed an arrested behavior specifically during P. berghei ANKA infection, despite the brain-accumulating CD8+ T cells exhibiting comparable activation phenotypes during both infections. We observed T cells forming long-term cognate interactions with CX3CR1-bearing antigen presenting cells within the brains during P. berghei ANKA infe...
Proceedings of the Royal Society B: Biological Sciences, 1994
Ion-selective microelectrodes were used to measure extracellular free ion concentrations in the r... more Ion-selective microelectrodes were used to measure extracellular free ion concentrations in the retina of the drone honeybee, Apis mellifera male. Mean values were (in millimoles per litre): Na+, 196; K+, 10.2; Ca2+, 2.0; pH 6.9. The elemental composition of fluid that rose into a micropipette inserted in the retina was obtained by electron microprobe X-ray analysis: from the concentrations of Na and K it was estimated that this fluid was 91% interstitial fluid. Amino acids and carbohydrates were analysed by chromatography. Four amino acids had concentrations > 20 mM: proline (109 mM), glutamine (38 mM), alanine (31 mM) and beta -alanine (24 mM). These concentrations were higher than in the haemolymph. Other amino acids had concentrations of less than 3 mM. The identified carbohydrates were trehalose, glucose, pyruvate and fructose. All of these were less concentrated than in the haemolymph. These results: (i) show that the ion concentrations of previously used Ringer solutions were reasonably correct; (ii) demonstrate properties of the blood-retina barrier; (iii) suggest that the extracellular concentration of alanine is ample for it to serve as a major substrate of neuronal energy metabolism in this tissue.
1. We have investigated changes in extracellular potassium concentration [K+]o in the supraoptic ... more 1. We have investigated changes in extracellular potassium concentration [K+]o in the supraoptic nucleus of lactating rats and in particular those that occur during the intense burst of firing by the oxytocin neurones involved in the milk ejection reflex. 2. Double-barrelled K(+)-selective microelectrodes containing a highly selective sensor based on valinomycin were lowered through the exposed cortex towards the supraoptic nucleus (SON) of female rats anaesthetized with urethane. The mean resting [K+]o in the hypothalami of five rats was 2.4 mM, S.D. = 0.3 mM. 3. Where the reference barrel recorded extracellular action potentials from an oxytocin cell, the reflex burst of firing (4 s, typical maximum 50 Hz) was accompanied by a mean increase in [K+]o (delta[K+]o) of 0.22 mM (S.E.M. = 0.02 mM, fifty-seven bursts in eight cells in seven rats). The rise in [K+]o did not begin more than 0.1 s before the onset of the burst, and began to fall from its maximum during the burst. Slow field...
... Permissions & Reprints. III. Glia-neuronal signaling Chapter 12. Metabolic trafficking be... more ... Permissions & Reprints. III. Glia-neuronal signaling Chapter 12. Metabolic trafficking between cells in nervous tissue. Jonathan A. Coles Corresponding Author Contact Information , 1 , E-mail The Corresponding Author , Céline Véga 2 , ** and Païkan Marcaggi 2 , ***. ...
There is significant evidence that brain-infiltrating CD8+ T cells play a central role in the dev... more There is significant evidence that brain-infiltrating CD8+ T cells play a central role in the development of experimental cerebral malaria (ECM) during Plasmodium berghei ANKA infection of C57BL/6 mice. However, the mechanisms through which they mediate their pathogenic activity during malaria infection remain poorly understood. Utilizing intravital two-photon microscopy combined with detailed ex vivo flow cytometric analysis, we show that brain-infiltrating T cells accumulate within the perivascular spaces of brains of mice infected with both ECM-inducing (P. berghei ANKA) and non-inducing (P. berghei NK65) infections. However, perivascular T cells displayed an arrested behavior specifically during P. berghei ANKA infection, despite the brain-accumulating CD8+ T cells exhibiting comparable activation phenotypes during both infections. We observed T cells forming long-term cognate interactions with CX3CR1-bearing antigen presenting cells within the brains during P. berghei ANKA infe...
Proceedings of the Royal Society B: Biological Sciences, 1994
Ion-selective microelectrodes were used to measure extracellular free ion concentrations in the r... more Ion-selective microelectrodes were used to measure extracellular free ion concentrations in the retina of the drone honeybee, Apis mellifera male. Mean values were (in millimoles per litre): Na+, 196; K+, 10.2; Ca2+, 2.0; pH 6.9. The elemental composition of fluid that rose into a micropipette inserted in the retina was obtained by electron microprobe X-ray analysis: from the concentrations of Na and K it was estimated that this fluid was 91% interstitial fluid. Amino acids and carbohydrates were analysed by chromatography. Four amino acids had concentrations > 20 mM: proline (109 mM), glutamine (38 mM), alanine (31 mM) and beta -alanine (24 mM). These concentrations were higher than in the haemolymph. Other amino acids had concentrations of less than 3 mM. The identified carbohydrates were trehalose, glucose, pyruvate and fructose. All of these were less concentrated than in the haemolymph. These results: (i) show that the ion concentrations of previously used Ringer solutions were reasonably correct; (ii) demonstrate properties of the blood-retina barrier; (iii) suggest that the extracellular concentration of alanine is ample for it to serve as a major substrate of neuronal energy metabolism in this tissue.
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