scholarly journals In vivo multiphoton microscopy of cardiomyocyte calcium dynamics in the beating mouse heart

2018 ◽  
Author(s):  
Jason S. Jones ◽  
David M. Small ◽  
Nozomi Nishimura
Keyword(s):  
Action Potentials ◽  
Multiphoton Microscopy ◽  
Three Dimensional ◽  
Heart Beat ◽  
Beating Heart ◽  
Mouse Heart ◽  
Calcium Dynamics ◽  
Intact Mouse ◽  
Calcium Indicator

AbstractWe demonstrated intravital multiphoton microscopy in the beating heart in an intact mouse and optically measured action potentials with GCaMP6f, a genetically-encoded calcium indicator. Images were acquired at 30 fps with spontaneous heart beat and continuously running ventilated breathing. The data were reconstructed into three-dimensional volumes showing tissue structure, displacement, and GCaMP activity in cardiomyocytes as a function of both the cardiac and respiratory cycle.

Intracellular recording from beating heart in situ using a special micropipette holder

1979 ◽  
Vol 237 (3) ◽  
pp. H392-H394 ◽  
Author(s):  
T. Akiyama ◽  
P. Serrino
Keyword(s):  
Intracellular Recording ◽  
Action Potentials ◽  
Heart Beat ◽  
Beating Heart ◽  
Ventricular Cells ◽  
Cardiac Hemodynamics ◽  
Transmembrane Action Potentials ◽  
Pharmacologic Agents

Use of a motion-compensated micropipette holder, which senses cardiac motion and lifts and lowers the micropipette and supporting apparatus in synchrony with the heart beat, allows for stable recording of transmembrane action potentials from subepicardial cells of an in vivo beating heart in an open-chest dog without significantly impairing cardiac hemodynamics. This technique may be used to study the effects of ischemia, hypertrophy, or pharmacologic agents on the cellular electrophysiological parameters of subepicardial ventricular cells of an in vivo beating heart.

Calcium Dynamics and Compartmentalization in Leech Neurons

2005 ◽  
Vol 94 (6) ◽  
pp. 4430-4440 ◽  
Author(s):  
Sofija Andjelic ◽  
Vincent Torre
Keyword(s):  
Information Processing ◽  
Action Potential ◽  
Action Potentials ◽  
Time Course ◽  
Ccd Camera ◽  
Calcium Dynamics ◽  
Single Action ◽  
Single Action Potential ◽  
Calcium Indicator ◽  
Mechanosensory Neurons

Calcium dynamics in leech neurons were studied using a fast CCD camera. Fluorescence changes (Δ F/ F) of the membrane impermeable calcium indicator Oregon Green were measured. The dye was pressure injected into the soma of neurons under investigation. Δ F/ F caused by a single action potential (AP) in mechanosensory neurons had approximately the same amplitude and time course in the soma and in distal processes. By contrast, in other neurons such as the Anterior Pagoda neuron, the Annulus Erector motoneuron, the L motoneuron, and other motoneurons, APs evoked by passing depolarizing current in the soma produced much larger fluorescence changes in distal processes than in the soma. When APs were evoked by stimulating one distal axon through the root, Δ F/ F was large in all distal processes but very small in the soma. Our results show a clear compartmentalization of calcium dynamics in most leech neurons in which the soma does not give propagating action potentials. In such cells, the soma, while not excitable, can affect information processing by modulating the sites of origin and conduction of AP propagation in distal excitable processes.

scholarly journals Three-photon imaging of synthetic dyes in deep layers of the neocortex

2020 ◽  
Author(s):  
Chao J. Liu ◽  
Arani Roy ◽  
Anthony A. Simons ◽  
Deano M. Farinella ◽  
Prakash Kara
Keyword(s):  
Multiphoton Microscopy ◽  
Synthetic Dyes ◽  
Visual Responses ◽  
Cortical Layers ◽  
Imaging Tool ◽  
Functional Dynamics ◽  
Calcium Indicator ◽  
Deep Layers ◽  
Photon Imaging

AbstractMultiphoton microscopy has emerged as the primary imaging tool for studying the structural and functional dynamics of neural circuits in brain tissue, which is highly scattering to light. Recently, three-photon microscopy has enabled high-resolution fluorescence imaging of neurons in deeper brain areas that lie beyond the reach of conventional two-photon microscopy, which is typically limited to ~450 μm. Three-photon imaging of neuronal calcium signals, through the genetically-encoded calcium indicator GCaMP6, has been used to successfully record neuronal activity in deeper neocortical layers and parts of the hippocampus. Bulk-loading cells in deeper cortical layers with synthetic calcium indicators could provide an alternative strategy for labelling that obviates dependence on viral tropism and promoter penetration. Here we report a strategy for visualized injection of a calcium dye, Oregon Green BAPTA-1 AM (OGB-1 AM), at 500–600 μm below the surface of the mouse visual cortex in vivo. We demonstrate successful OGB-1 AM loading of cells in cortical layers 5–6 and subsequent three-photon imaging of orientation- and direction-selective visual responses from these cells.

scholarly journals Monitoring Presynaptic Calcium Dynamics in Projection Fibers by In Vivo Loading of a Novel Calcium Indicator

Neuron ◽  
2000 ◽  
Vol 27 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Anatol C Kreitzer ◽  
Kyle R Gee ◽  
Eric A Archer ◽  
Wade G Regehr
Keyword(s):  
Calcium Dynamics ◽  
Calcium Indicator ◽  
Presynaptic Calcium ◽  
In Vivo Loading

scholarly journals Mechanical mapping of mammalian follicle development using Brillouin microscopy

2021 ◽  
Author(s):  
Chii Jou Chan ◽  
Carlo Bevilacqua ◽  
Robert Prevedel
Keyword(s):  
Material Properties ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Follicle Development ◽  
Mammalian Development ◽  
Oocyte Growth ◽  
Intact Mouse ◽  
Matrix Deposition

AbstractIn early mammalian development, the maturation of follicles containing the immature oocytes is an important biological process as the functional oocytes provide the bulk genetic and cytoplasmic materials for successful reproduction. Despite recent work demonstrating the regulatory role of mechanical stress in oocyte growth, quantitative studies of ovarian mechanical properties remain lacking both in vivo and ex vivo. In this work, we quantify the material properties of ooplasm, follicles and connective tissues in intact mouse ovaries at distinct stages of follicle development using Brillouin microscopy, a non-invasive tool to probe mechanics in three-dimensional (3D) tissues. We find that the ovarian cortex and its interior stroma have distinct material properties associated with extracellular matrix deposition, and that intra-follicular mechanical compartments emerge during follicle maturation. Our work provides a novel approach to study the role of mechanics in follicle morphogenesis and pave the way for future understanding of mechanotransduction in reproductive biology, with potential implications for infertility diagnosis and treatment.

scholarly journals Mechanical mapping of mammalian follicle development using Brillouin microscopy

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Chii Jou Chan ◽  
Carlo Bevilacqua ◽  
Robert Prevedel
Keyword(s):  
Material Properties ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Follicle Development ◽  
Mammalian Development ◽  
Oocyte Growth ◽  
Intact Mouse ◽  
Matrix Deposition

AbstractIn early mammalian development, the maturation of follicles containing the immature oocytes is an important biological process as the functional oocytes provide the bulk genetic and cytoplasmic materials for successful reproduction. Despite recent work demonstrating the regulatory role of mechanical stress in oocyte growth, quantitative studies of ovarian mechanical properties remain lacking both in vivo and ex vivo. In this work, we quantify the material properties of ooplasm, follicles and connective tissues in intact mouse ovaries at distinct stages of follicle development using Brillouin microscopy, a non-invasive tool to probe mechanics in three-dimensional (3D) tissues. We find that the ovarian cortex and its interior stroma have distinct material properties associated with extracellular matrix deposition, and that intra-follicular mechanical compartments emerge during follicle maturation. Our work provides an alternative approach to study the role of mechanics in follicle morphogenesis and might pave the way for future understanding of mechanotransduction in reproductive biology, with potential implications for infertility diagnosis and treatment.

scholarly journals Lipopolysaccharide-induced neuroinflammation disrupts functional connectivity and community structure in primary cortical microtissues

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Elaina Atherton ◽  
Sophie Brown ◽  
Emily Papiez ◽  
Maria I. Restrepo ◽  
David A. Borton
Keyword(s):  
Community Structure ◽  
Functional Connectivity ◽  
Three Dimensional ◽  
Theory Analysis ◽  
Disease States ◽  
Calcium Indicator ◽  
Graph Theory Analysis

AbstractThree-dimensional (3D) neural microtissues are a powerful in vitro paradigm for studying brain development and disease under controlled conditions, while maintaining many key attributes of the in vivo environment. Here, we used primary cortical microtissues to study the effects of neuroinflammation on neural microcircuits. We demonstrated the use of a genetically encoded calcium indicator combined with a novel live-imaging platform to record spontaneous calcium transients in microtissues from day 14–34 in vitro. We implemented graph theory analysis of calcium activity to characterize underlying functional connectivity and community structure of microcircuits, which are capable of capturing subtle changes in network dynamics during early disease states. We found that microtissues cultured for 34 days displayed functional remodeling of microcircuits and that community structure strengthened over time. Lipopolysaccharide, a neuroinflammatory agent, significantly increased functional connectivity and disrupted community structure 5–9 days after exposure. These microcircuit-level changes have broad implications for the role of neuroinflammation in functional dysregulation of neural networks.

Subthreshold somatic voltage in neocortical pyramidal cells can control whether spikes propagate from the axonal plexus to axon terminals: a model study

2012 ◽  
Vol 107 (10) ◽  
pp. 2833-2852 ◽  
Author(s):  
Erin Munro ◽  
Nancy Kopell
Keyword(s):  
Gap Junctions ◽  
Pyramidal Cell ◽  
Action Potentials ◽  
Three Dimensional ◽  
Pyramidal Cells ◽  
Axon Terminals ◽  
Model Study ◽  
Rat Somatosensory Cortex ◽  
Fast Oscillations

There is suggestive evidence that pyramidal cell axons in neocortex may be coupled by gap junctions into an “axonal plexus” capable of generating very fast oscillations (VFOs) with frequencies exceeding 80 Hz. It is not obvious, however, how a pyramidal cell in such a network could control its output when action potentials are free to propagate from the axons of other pyramidal cells into its own axon. We address this problem by means of simulations based on three-dimensional reconstructions of pyramidal cells from rat somatosensory cortex. We show that somatic depolarization enables propagation via gap junctions into the initial segment and main axon, while somatic hyperpolarization disables it. We show further that somatic voltage cannot effectively control action potential propagation through gap junctions on minor collaterals; action potentials may therefore propagate freely from such collaterals regardless of somatic voltage. In previous work, VFOs are all but abolished during the hyperpolarization phase of slow oscillations induced by anesthesia in vivo. This finding constrains the density of gap junctions on collaterals in our model and suggests that axonal sprouting due to cortical lesions may result in abnormally high gap junction density on collaterals, leading in turn to excessive VFO activity and hence to epilepsy via kindling.

Action potential characterization in intact mouse heart: steady-state cycle length dependence and electrical restitution

2007 ◽  
Vol 292 (1) ◽  
pp. H614-H621 ◽  
Author(s):  
Björn C. Knollmann ◽  
Tilmann Schober ◽  
Andreas O. Petersen ◽  
Syevda G. Sirenko ◽  
Michael R. Franz
Keyword(s):  
Steady State ◽  
Action Potential ◽  
Action Potentials ◽  
Cycle Length ◽  
Molecular Mechanisms ◽  
Left Ventricular ◽  
Monophasic Action Potential ◽  
Mouse Heart ◽  
Intact Mouse ◽  
Length Dependence

Transgenic mice have been increasingly utilized to investigate the molecular mechanisms of cardiac arrhythmias, yet the rate dependence of the murine action potential duration and the electrical restitution curve (ERC) remain undefined. In the present study, 21 isolated, Langendorff-perfused, and atrioventricular node-ablated mouse hearts were studied. Left ventricular and left atrial action potentials were recorded using a validated miniaturized monophasic action potential probe. Murine action potentials (AP) were measured at 30, 50, 70, and 90% repolarization (APD30–APD90) during steady-state pacing and varied coupling intervals to determine ERCs. Murine APD showed rate adaptation as well as restitution properties. The ERC time course differed dramatically between early and late repolarization: APD30 shortened with increasing S1–S2 intervals, whereas APD90 was prolonged. When fitted with a monoexponential function, APD30 reached plateau values significantly faster than APD90 (τ = 29 ± 2 vs. 78 ± 6 ms, P < 0.01, n = 12). The slope of early APD90 restitution was significantly <1 (0.16 ± 0.02). Atrial myocardium had shorter final repolarization and significantly faster ERCs that were shifted leftward compared with ventricular myocardium. Recovery kinetics of intracellular Ca2+ transients recorded from isolated ventricular myocytes at 37°C (τ = 93 ± 4 ms, n = 18) resembled the APD90 ERC kinetics. We conclude that mouse myocardium shows AP cycle length dependence and electrical restitution properties that are surprisingly similar to those of larger mammals and humans.

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