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Author (up) Bajji, M.; Kinet, J.-M.; Lutts, S. file  url
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  Title Salt stress effects on roots and leaves of Atriplex halimus L. and their corresponding callus cultures Type Journal Article
  Year 1998 Publication Plant Science Abbreviated Journal Plant Science  
  Volume 137 Issue 2 Pages 131-142  
  Keywords Atriplex halimus L.; Ion accumulation; Osmotic adjustment; Organic solutes; Salinity; Tissue culture  
  Abstract Salt stress effects on growth, osmotic adjustment, mineral and organic contents and soluble peroxidase activities were determined in roots and leaves of Atriplex halimus and their corresponding callus cultures. Low NaCl doses (150 mM) promoted shoot growth, corroborating the halophilic nature of this species; in these stress conditions, Na+ concentration markedly increased in the leaves indicating that salinity resistance was not associated with the ability of the plants to restrict sodium accumulation in the aerial part. Whole organs and their corresponding calli were able to cope with high NaCl doses but there was no clear correspondence between the physiological behaviour of cell culture and whole plant. For several physiological parameters (osmotic potential (Ψs), mineral content, proline accumulation), roots were less affected by NaCl than leaves while both root and leaf calli behaved in the same way in response to salinity. NaCl-induced modifications of the recorded parameters are discussed in relation to the mechanisms of salinity resistance in this species. Evidence indicated the existence of a cellular basis for salinity resistance in A. halimus, but the expression of this cellular property at organ level appeared to be masked by the physiological complexity of the intact plant and the nature of the whole organ response was apparently determined primarily by regulation mechanisms assigned by the differentiated tissue organization.  
  Call Number Serial 683  
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Author (up) Ribeiro, P.O.; Tome, A.R.; Silva, H.B.; Cunha, R.A.; Antunes, L.M. file  url
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  Title Clinically relevant concentrations of ketamine mainly affect long-term potentiation rather than basal excitatory synaptic transmission and do not change paired-pulse facilitation in mouse hippocampal slices Type Journal Article
  Year 2014 Publication Brain Research Abbreviated Journal Brain Res  
  Volume 1560 Issue Pages 10-17  
  Keywords Afferent Pathways/drug effects/physiology; Anesthetics/*pharmacology; Animals; CA1 Region, Hippocampal/drug effects/physiology; CA3 Region, Hippocampal/drug effects/physiology; Dose-Response Relationship, Drug; Electric Stimulation; Excitatory Postsynaptic Potentials/drug effects; Female; Hippocampus/*drug effects/physiology; Ketamine/*pharmacology; Long-Term Potentiation/*drug effects; Mice, Inbred BALB C; Microelectrodes; Neuronal Plasticity/*drug effects/physiology; Presynaptic Terminals/drug effects/physiology; Pyramidal Cells/drug effects/physiology; Synaptic Transmission/*drug effects; Tissue Culture Techniques; Hippocampus; Ketamine; Synaptic plasticity; Synaptic transmission  
  Abstract Ketamine, an analgesic/anesthetic drug, is increasingly popular in clinical practice due to its analgesic properties and importance for emergency procedures. The impact of ketamine on basal excitatory synaptic transmission and synaptic plasticity are not yet fully understood. Therefore we investigated the effects of different concentrations of ketamine on basal excitatory synaptic transmission and on two forms of synaptic plasticity: paired-pulse facilitation (PPF) and long-term potentiation (LTP). Evoked field excitatory postsynaptic potentials (fEPSP) were recorded in Schaffer fiber – CA1 pyramid synapses of mouse hippocampal slices and the initial slope of the fEPSP was measured to estimate the percentage of inhibition of the basal synaptic transmission. Presynaptic volley amplitude, PPF and LTP induction and maintenance were also calculated. For basal synaptic transmission and PPF increasing concentrations of ketamine (1, 3, 10, 30, 100, 200, 300 and 600muM) were applied to each slice and for LTP individual slices were used for each concentration (3, 10, 30 or 100muM). Clinically relevant concentrations of ketamine decreased LTP in a concentration-dependent manner without changing PPF, whereas basal excitatory synaptic transmission and presynaptic volley amplitude was affected only with high concentrations of ketamine (300 and 600muM). These results allow dissociating the blockade of LTP from a reduced synaptic input in the action of clinically relevant concentrations of ketamine in the CA1 region of the mouse hippocampus. Moreover, this work shows that the effects of ketamine on LTP and on basal synaptic transmission are dependent of the concentration used.  
  Call Number Serial 1002  
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