I am doing calcium flux imaging with your Fura-2 calibration kit, but am seeing a large variability in ratio in different places around the slide. I am correcting for uniform illumination, using the product as directed, and sealing the coverslip with nail polish.
The nail polish may be the problem. The Kd value (calcium sensitivity) changes depending upon the dye's environment. Nail polish has solvents that can leech under the coverslip and cause variability. We recommend either going without a sealing or sealing with melted paraffin painted on the coverslip edges with a cotton-tipped applicator (paraffin is hydrophobic and has no solvents).
I need to label cells with Fluo-4, AM, for a calcium flux assay. How long after labeling will the dye be retained?
After loading dye into the cells, intracellular esterases remove the 'AM' moiety from the dye. When the 'AM' group is removed, the dye is able to bind calcium and fluoresce. Since the dye is not covalently bound to any cellular components, it may be actively effluxed from the cell. The rate of efflux is dependent upon the inherent properties of the cell, culture conditions and other factors. The dye may be retained for hours, days or even weeks or lost in a matter of minutes. The use of Probenecid (Cat. No. P36400) limits loss by active efflux.
LIM domain only 4 (LMO4) regulates calcium-induced calcium release and synaptic plasticity in the hippocampus.
Authors:Qin Z, Zhou X, Gomez-Smith M, Pandey NR, Lee KF, Lagace DC, Béïque JC, Chen HH,
Journal:J Neurosci
PubMed ID:22442089
'The LIM domain only 4 (LMO4) transcription cofactor activates gene expression in neurons and regulates key aspects of network formation, but the mechanisms are poorly understood. Here, we show that LMO4 positively regulates ryanodine receptor type 2 (RyR2) expression, thereby suggesting that LMO4 regulates calcium-induced calcium release (CICR) in central ... More
nNOS(+) striatal neurons, a subpopulation spared in Huntington's Disease, possess functional NMDA receptors but fail to generate mitochondrial ROS in response to an excitotoxic challenge.
'Huntington''s disease (HD) is a neurodegenerative condition characterized by severe neuronal loss in the cortex and striatum that leads to motor and behavioral deficits. Excitotoxicity is thought to be involved in HD and several studies have indicated that NMDA receptor (NMDAR) overactivation can play a role in the selective neuronal ... More
Mechanisms underlying cannabinoid inhibition of presynaptic Ca2+ influx at parallel fibre synapses of the rat cerebellum.
Authors:Daniel H, Rancillac A, Crepel F
Journal:J Physiol
PubMed ID:15034129
'Activation of CB1 cannabinoid receptors in the cerebellum acutely depresses excitatory synaptic transmission at parallel fibre-Purkinje cell synapses by decreasing the probability of glutamate release. This depression involves the activation of presynaptic 4-aminopyridine-sensitive K(+) channels by CB1 receptors, which in turn inhibits presynaptic Ca(2+) influx controlling glutamate release at these ... More
Cross-tolerance to otherwise lethal N-methyl-D-aspartate and oxygen-glucose deprivation in preconditioned cortical cultures.
Authors:Tauskela JS, Comas T, Hewitt K, Monette R, Paris J, Hogan M, Morley P
Journal:Neuroscience
PubMed ID:11720781
'In vitro ischemic preconditioning induced by subjecting rat cortical cultures to nonlethal oxygen-glucose deprivation protects against a subsequent exposure to otherwise lethal oxygen-glucose deprivation. We provide evidence that attenuation of the postsynaptic N-methyl-D-aspartate (NMDA) receptor- and Ca(2+)-dependent neurotoxicity underlies oxygen-glucose deprivation tolerance. It is demonstrated that extended tolerance to otherwise ... More
Mitochondrial calcium uniporter silencing potentiates caspase-independent cell death in MDA-MB-231 breast cancer cells.
'The mitochondrial calcium uniporter (MCU) transports free ionic Ca(2+) into the mitochondrial matrix. We assessed MCU expression in clinical breast cancer samples using microarray analysis and the consequences of MCU silencing in a breast cancer cell line. Our results indicate that estrogen receptor negative and basal-like breast cancers are characterized ... More