Calcium waves in gray matter are due to voltage-sensitive glial membrane channels

Lima, Vera Maura Fernandes de; Goldermann, M.; Hanke, Wolfgang

doi:10.1016/0006-8993(94)90464-2

Cited by 14 publications

(20 citation statements)

References 9 publications

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“…As already mentioned, we were able to distinguish two different spectral parts of the IOS in an earlier paper [Fernandes de Lima et al, 1994], which show peak light reflections in the green (500 nm) and red (625 nm) part of the visible light. Their properties are different, since the green signal is uniform and continuous in space and time, while the red signal is not.…”

Section: Resultssupporting

confidence: 55%

“…They differ in their spectral preference, in their spatiotemporal characteristics and in their response to experimental manipulations [Martins-Ferreira & De Oliveira Castro, 1966;Fernandes de Lima et al, 1994]. Propagating excitation waves have been observed in a variety of systems [Müller & Plesser, 1992] and a solid pool of literature exists.…”

Section: Introductionmentioning

confidence: 99%

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Observations on the Onset and Propagation of Excitation Waves in Neural Tissue

Goldermann

Hanke

Almeida³

et al. 1998

Int. J. Bifurcation Chaos

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The onset and propagation of waves in an excitable medium were investigated using the retinal Spreading Depression (rSD). The rSD is an ideal tool for this purpose. The retina of chicken, which was used in all experiments, is a close to two-dimensional system, in which the wave can easily be observed by optical techniques in time and space. rSD waves can be elicited by a variety of stimuli. Between stimulus and onset of the wave a temporal delay is always present. We found that the wave velocity is a function of the duration of this delay. In this paper we show, that within this time increasing fluctuations occur of system parameters.Another set of experiments deals with spatial correlations in the rSD. In some experiments we found the onset of the wave to be about 300 µm locally displaced with respect to the point of stimulus.In collision experiments, the spread velocity of two wavefronts approaching each other was measured. We found a significant increase in the velocity. This increase in velocity takes place on the last 250 µm before collision. This distance resembles the one found for local displacements, indicating a common origin.

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Section: Resultssupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Observations on the Onset and Propagation of Excitation Waves in Neural Tissue

Goldermann

Hanke

Almeida³

et al. 1998

Int. J. Bifurcation Chaos

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“…The eyes were cut parallel to the lens at the equator, the vitreous humour removed and the posterior chamber transferred to a Petri dish containing the following Ringer solution: 100 mM NaCl, 6 mM KCl, 1 mM MgSO 4 , 1 mM CaCl 2 , 1 mM NaH 2 PO 4 , 30 mM NaHCO 3 , 10 mM TRIS and 30 mM glucose (Fernandes de Lima et al 1994). The pH was adjusted to 7.4 by titration with HCl.…”

Section: Methodsmentioning

confidence: 99%

Pharmacological modulation of the refractory period of retinal spreading depression

Brand

Lima²,

Hanke

1998

Naunyn-Schmiedeberg's Arch Pharmacol

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Spreading depression (SD) is a propagating wave of neuronal activity in the central nervous system and may play a role in triggering classical migraine. The retina serves as a model system for examining the phenomenon of SD and the influence of various drugs on it. After a SD wave passes a new wave can not be elicited in the absolute refractory period of the tissue (about 2 min), this is followed by a relative refractory phase of about 20 min before complete recovery. The aim of the present study was to describe the effects of Ba2+, a blocker of glial cell K+ channels, octanol, a gap junction blocker and diethylbarbiturate, a GABA(A) chloride channel-activating drug on the modulation of the refractory period of the retinal SD and to examine the possible mechanisms underlying this modulation. Two properties of SD, which are highly sensitive to any changes in the experimental conditions, are the propagation velocity of the wave and the accompanying slow negative potential shift. We measured the propagation velocity and the field potential amplitude in the chicken retina as a function of the recovery state of the tissue under control conditions and compared them with measurements in the presence of Ba2+, octanol or diethylbarbiturate. Under these conditions the manner of the recovery of the tissue changed significantly. Although after blocking the glial (Müller) cell K+ channels with Ba2+ (200 microM), the curve of recovery of the propagation velocity to its maximum value has the same shape as under control conditions, the propagation velocity is reduced in the whole recovery period and in the recovered retina to 84% of the control velocity. The importance of electrical coupling in the refractory phase and in the recovered tissue was examined by adding octanol (1 mM) to the perfusion solution. In this case the relative recovery phase was shortened and the field potential amplitude (110% of control) and propagation velocity (112% of control) are increased in the completely recovered retina. With the GABA(A)-chloride channel-activating drug diethylbarbiturate (800 microM) the propagation velocity (112% of control) and the amplitude of the field potential (111% of control) in the complete recovered retina are increased, but this seems to have no influence on the refractory state.

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“…Furthermore, we believe that the measured parameter (the scattered red component of the IOS of RSDs) in these previous experiments is closely related to the bulk potential changes during SDs (Fernandes de Lima et al 1994, Fernandes de Lima andHanke 1997) permitting an indirect visualization of membrane events in the tissue. This scatter is a macroscopic concomitant, obviously at a suprasynaptic scale of organization.…”

Section: Introductionmentioning

confidence: 99%

“…A temporal delay existed between the stimulation of the system and the onset of propagation Hanke 1996, Brand andHanke 1996); 2. Fluctuations in the red scatter preceded the wave in space (Fernandes de Lima et al 1994); 3. A spatial displacement of wave onset due to mechanical stimulation was possible, due to long range interactions (Fernandes de Lima and Hanke 1996).…”

Section: Introductionmentioning

confidence: 99%

Wave onset in central gray matter - its intrinsic optical signal and phase transitions in extracellular polymers

Fernandes-De-Lima

Kogler

Bennaton

et al. 2001

An. Acad. Bras. Ciênc.

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The brain is an excitable media in which excitation waves propagate at several scales of time and space. ''Onedimensional'' action potentials (millisecond scale) along the axon membrane, and spreading depression waves (seconds to minutes) at the three dimensions of the gray matter neuropil (complex of interacting membranes) are examples of excitation waves. In the retina, excitation waves have a prominent intrinsic optical signal (IOS). This optical signal is created by light scatter and has different components at the red and blue end of the spectrum. We could observe the wave onset in the retina, and measure the optical changes at the critical transition from quiescence to propagating wave. The results demonstrated the presence of fluctuations preceding propagation and suggested a phase transition. We have interpreted these results based on an extrapolation from Tasaki's experiments with action potentials and volume phase transitions of polymers. Thus, the scatter of red light appeared to be a volume phase transition in the extracellular matrix that was caused by the interactions between the cellular membrane cell coat and the extracellular sugar and protein complexes. If this hypothesis were correct, then forcing extracellular current flow should create a similar signal in another tissue, provided that this tissue was also transparent to light and with a similarly narrow extracellular space. This control tissue exists and it is the crystalline lens. We performed the experiments and confirmed the optical changes. Phase transitions in the extracellular polymers could be an important part of the long-range correlations found during wave propagation in central nervous tissue.

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Calcium waves in gray matter are due to voltage-sensitive glial membrane channels

Cited by 14 publications

References 9 publications

Observations on the Onset and Propagation of Excitation Waves in Neural Tissue

Observations on the Onset and Propagation of Excitation Waves in Neural Tissue

Pharmacological modulation of the refractory period of retinal spreading depression

Wave onset in central gray matter - its intrinsic optical signal and phase transitions in extracellular polymers

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