Barium ions fail to support neurotransmission at a central synapse

Medina, Joanna; Barden, S.D.; Davies, Morgan; Newell, B.A.T.; Shaw, Susan; Willis, Monte S.; Halliwell, J. V.

doi:10.1016/0304-3940(94)90427-8

Cited by 7 publications

(4 citation statements)

References 18 publications

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“…Halliwell, 1990). In view of the inability of Ba 2+ to support synaptic transmission (Medina et al ., 1994) the experiments manipulating divalent cations were anticipated to affect neuronal excitability in preference to synaptic transmission. Hence, and in contrast to the effects of raised Ca 2+ , 1 m m Ba 2+ applied to the slices caused a potentiation of the negative notch (median potentiation, 70%, n = 7, P < 0.05) and a slight but nonsignificant depression of synaptic transmission (median depression, 9%) (Fig.…”

Section: Resultsmentioning

confidence: 99%

Electrophysiological characterization of laminar synaptic inputs to the olfactory tubercle of the rat studied in vitro: modulation of glutamatergic transmission by cholinergic agents is pathway‐specific

Owen

Halliwell

2001

Eur J of Neuroscience

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We have exploited the complementary arrangement of afferents in a coronal slice (300-400 microm) of the rat olfactory tubercle (OT) maintained in vitro to investigate transmission in two separate synaptic pathways. We recorded extracellular responses within the OT dense cell layer in slices and stimulated either the outermost layer to activate primary olfactory fibres or deeper to activate secondary input. Superficial stimulation produced a synaptic potential with superimposed population spike. This interpretation was based on blockade by calcium removal from the bathing medium and the use of the glutamate antagonist DNQX (10 microM); the spike was found to be selectively suppressed by tetrodotoxin applied near the cells. The spike, but not the synaptic wave, was depressed by 12 mM Ca2+ and enhanced by 1 mM Ba2+ in the bathing medium. Deep stimulation to activate association and intrinsic fibres elicited a nerve volley followed by a later response, also blocked by Ca2+ removal or 10 microM DNQX. It was unaffected by high Ca2+ or Ba2+, hence resulting from synaptic and not action current flow. Removal of Mg2+ from the bathing medium revealed an NMDA component of synaptic transmission at both loci that was selectively blocked by D-AP-5. The deep synaptic response, only, was depressed by carbachol IC50 7 microM or muscarine IC50 13 microM. This depression was also induced by AChE inhibitors eserine or tacrine and was antagonized by 1 microM atropine or 5-10 microM clozapine. These results characterize transmission in the OT and demonstrate a role for muscarinic modulation of deeper synapses in the OT that is influenced by psychotherapeutic drugs.

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Section: Resultsmentioning

confidence: 99%

Electrophysiological characterization of laminar synaptic inputs to the olfactory tubercle of the rat studied in vitro: modulation of glutamatergic transmission by cholinergic agents is pathway‐specific

Owen

Halliwell

2001

Eur J of Neuroscience

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“…The binding of Ca 2+ to the EF‐hand proteins α‐lactalbumin (Eberhard & Erne, 1991) and parvalbumin (Permyakov et al 1983; Eberhard & Erne, 1994) is also inhibited by Na + . Previous studies have shown that synchronous synaptic transmission is maintained when external Ca 2+ is replaced by Sr 2+ , but is supported to only a small extent, or not at all, by external Ba 2+ (Dodge et al 1969; Alvarez‐Leefmans et al 1978; Augustine & Eckert, 1984; Medina et al 1994; Ohno‐Shosaku et al 1994). Thus, the ion selectivity of both synchronous synaptic transmission and the fast component of exocytosis in PC12 cells is more stringent than that of exocytosis of LVs.…”

Section: Discussionmentioning

confidence: 99%

“…Exocytosis of LVs from endocrine cells is supported when external Ca 2+ is replaced with Ba 2+ (Berggren, 1981; Douglas et al 1983; Brown et al 1990; von Ruden et al 1993; Seward et al 1996; Borges et al 1997; Nucifora & Fox, 1998). In contrast, synchronous SV exocytosis from presynaptic terminals is not maintained by Ba 2+ in the external solution (Dodge et al 1969; Alvarez‐Leefmans et al 1978; Augustine & Eckert, 1984; Medina et al 1994; but see Ohno‐Shosaku et al 1994), although Ba 2+ does support asynchronous slow neurotransmitter release (Silinsky, 1978; McMahon & Nicholls, 1993; Sihra et al 1993; Verhage et al 1995). None of these studies, however, examined the effects of divalent cations introduced directly into the cytosol.…”

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confidence: 99%

Ion selectivities of the Ca²⁺ sensors for exocytosis in rat phaeochromocytoma cells

Kishimoto

Liu

Ninomiya

et al. 2001

The Journal of Physiology

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“…Barium iodide (Ba Lα 1 =4.5 keV, I Lα 1 =3.9 keV) is a highly soluble salt that would normally be readily dispersed in the body, with iodide being consequently naturally concentrated in the thyroid19, while barium ions are toxic, interfering with muscular and neuronal Ca 2+ transport20. Successful confinement of BaI 2 within a CNT2122 would therefore provide a powerful system for the alteration of this typical, toxic biodistribution.…”

Section: Resultsmentioning

confidence: 99%

Carbon nanotubes allow capture of krypton, barium and lead for multichannel biological X-ray fluorescence imaging

et al. 2016

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The desire to study biology in situ has been aided by many imaging techniques. Among these, X-ray fluorescence (XRF) mapping permits observation of elemental distributions in a multichannel manner. However, XRF imaging is underused, in part, because of the difficulty in interpreting maps without an underlying cellular ‘blueprint'; this could be supplied using contrast agents. Carbon nanotubes (CNTs) can be filled with a wide range of inorganic materials, and thus can be used as ‘contrast agents' if biologically absent elements are encapsulated. Here we show that sealed single-walled CNTs filled with lead, barium and even krypton can be produced, and externally decorated with peptides to provide affinity for sub-cellular targets. The agents are able to highlight specific organelles in multiplexed XRF mapping, and are, in principle, a general and versatile tool for this, and other modes of biological imaging.

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Barium ions fail to support neurotransmission at a central synapse

Cited by 7 publications

References 18 publications

Electrophysiological characterization of laminar synaptic inputs to the olfactory tubercle of the rat studied in vitro: modulation of glutamatergic transmission by cholinergic agents is pathway‐specific

Electrophysiological characterization of laminar synaptic inputs to the olfactory tubercle of the rat studied in vitro: modulation of glutamatergic transmission by cholinergic agents is pathway‐specific

Ion selectivities of the Ca²⁺ sensors for exocytosis in rat phaeochromocytoma cells

Carbon nanotubes allow capture of krypton, barium and lead for multichannel biological X-ray fluorescence imaging

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Barium ions fail to support neurotransmission at a central synapse

Cited by 7 publications

References 18 publications

Electrophysiological characterization of laminar synaptic inputs to the olfactory tubercle of the rat studied in vitro: modulation of glutamatergic transmission by cholinergic agents is pathway‐specific

Electrophysiological characterization of laminar synaptic inputs to the olfactory tubercle of the rat studied in vitro: modulation of glutamatergic transmission by cholinergic agents is pathway‐specific

Ion selectivities of the Ca2+ sensors for exocytosis in rat phaeochromocytoma cells

Carbon nanotubes allow capture of krypton, barium and lead for multichannel biological X-ray fluorescence imaging

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Ion selectivities of the Ca²⁺ sensors for exocytosis in rat phaeochromocytoma cells