M. O. K. Enkvist

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Astroglia are extensively coupled by gap junctions and form a functional syncytium. Astroglial gap junctions are thought to be involved in the spatial buffering of K+ in vivo and in the Ca2+ waves seen on glutamate receptor activation. The conductivity of gap junctions is regulated by several second messengers, with up-regulation by cyclic AMP and(More)
The following two processes related to astrocytes are thought to depend on intercellular coupling through gap junctions: the spatial buffering of K+o and the spread of calcium waves in the astrocytic syncytium. We have used the following two independent methods to measure the open state of gap junctions: injection of lucifer yellow, and optical calcium(More)
The relation between intracellular and extracellular [Na+] and [Ca2+] and membrane potential during stimulation of non-N-methyl-D-aspartate glutamate receptors has been studied in cerebellar granule cells using the fluorescent indicators SBFI, fura-2 and the bisoxonol membrane potential probe DiBaC4(3). Kainate increased both [Ca2+]i (intracellular [Ca2+])(More)
Gastropancreatic neuroendocrine cells synthesize large amounts of γ-aminobutyric acid (GABA). This amino acid neurotransmitter appears to be stored in and released from, vesicles similar to small synaptic vesicles. So far, the function of GABA in gastropancreatic, neuroendocrine cells has not been clarified. Previous work suggested that only pancreatic,(More)
Communication across gap junctions between cells in various tissues is considered an important mechanism for control of cellular growth, differentiation and function. Although cell-cell coupling in the gill epithelium is likely for functional reasons, the common view is that gap junctions are not present between cells in the gill epithelium of teleostean(More)
We have investigated which alpha 2-receptor subtypes are expressed in cultured cortical astroglia, and their coupling to second messengers. Binding assays using [3H]rauwolscine showed a very low number of alpha 2 receptors in the astrocytic cultures. Treatment of cultures with dibutyryl cyclic AMP (dBcAMP) increased significantly the number of receptors.(More)
Both phenylephrine and carbachol caused a sustained increase in Ca2+ influx and intracellular free Ca2+ of primary astrocytes as measured with 45Ca2+ and fura-2. The responses to phenylephrine and carbachol were additive, suggesting that they use different releasable pools of Ca2+. If extracellular Ca2+ was removed by EGTA only a transient rise in cytosolic(More)
The cyanine dye DiS-C2-(5) was used to investigate the effect of K+ and glutamate receptor agonists on the membrane potential of whole populations of primary rat astrocytes in suspension. Increasing the external K+ concentration from 5 to 40 mM caused a depolarization of the cells. Ba2+ blocked the response to K+, whereas 4-aminopyridine had no effect on(More)
Owing to an error in the production process the afilliation of the above-mentioned article has been mistakenly interchanged. The affilation as it should have been printed is presented below: Department of Biology and ∗Department of Biochemistry, Åbo Akademi University, BioCity, Artilleriegatan 6, 20520 Turku/Åbo, Finland; (Phone: +358 21 654 065. Fax: +358(More)
The membrane potential of astrocytes has been measured by monitoring the absorbance of a cyanine dye DiS-C2-(5). Ba2+, the phorbol ester 12-tetradecanoylphorbol myristateacetate (TPA) and the diglyceride, dioctanoylglycerol (DiC8) depolarize the membrane. Valinomycin which makes the membrane potential dependent on the K+ electrochemical potential evokes a(More)