S1. Imaging seminar Flashcards
What is the primary role of calcium in cardiac contraction
Triggering muscle contraction by enabling actin-myosin cross-bridge formation
How does calcium regulate mitochondrial ATP production
By modulating matrix enzymes like pyruvate and glutamate dehydrogenase
What is the significance of minimal ATP reserves in the heart
It emphasizes the need for continuous ATP production by mitochondria
What is the function of ‘Rhod-2’ in experiments
To measure cytosolic calcium levels
What does ‘MityCam’ specifically measure
Mitochondrial calcium levels
What experimental tool quantifies mitochondrial calcium influx
Stopped-flow fluorometry with Rhod-2 and Fura-2
Which metabolic substrates enhance calcium-sensitive ATP production
Pyruvate and glutamate
What is the role of the mitochondrial calcium uniporter (MCU)
It transports calcium into the mitochondrial matrix
What happens to mitochondrial membrane potential (ΔΨm) at high workloads
It is maintained by calcium-sensitive NADH production
Why is calcium sensitivity important for mitochondrial ATP production
It allows ATP synthesis to match the workload dynamically
What is the unique feature of mammalian ATP synthase compared to bacterial
Higher voltage threshold and non-saturating ATP production curve
What is the role of ΔΨm in ATP production
ΔΨm provides the driving force for ATP synthesis by ATP synthase
Why is studying mitochondrial calcium signaling challenging
Due to sparse MCU channels and low conductance
What is the physiological relevance of ΔΨm maintenance during high workload
Ensures sustained ATP production without ΔΨm collapse
Why are MCU channels considered sparse
Only 15-65 channels per mitochondrion in cardiac tissue
How does high ADP affect mitochondrial membrane potential
It depolarizes ΔΨm unless calcium is elevated
What is the effect of elevated inorganic phosphate on ATP production
It diminishes ATP production at super-physiological levels
Why does ATP production depend on ΔΨm
It is driven by proton influx through ATP synthase
What is the role of luciferase in ATP production assays
To measure ATP levels via luminescence
Why is pyruvate crucial in ATP production experiments
It enables calcium-sensitive ATP production pathways
What technique is used to assess ΔΨm quantitatively
Tetramethylrhodamine methyl ester (TMRM) fluorescence
Why is ΔΨm critical in cardiovascular health
It supports sustained ATP production for heart function
What does MCU dysfunction imply for ATP production
Impaired calcium uptake disrupts NADH generation and ATP synthesis
How might altered calcium signaling contribute to heart disease
It can lead to inadequate ATP production under stress conditions
What is the unexpected behavior of ATP synthase at high ΔΨm
ATP production exceeds expected rates, suggesting adaptive stoichiometry
What is adaptive stoichiometry in ATP synthase
Increased protons per ATP produced at hyperpolarized ΔΨm
What is the effect of isoproterenol on calcium dynamics
It elevates both cytosolic and mitochondrial calcium transients
Why is studying ΔΨm-voltage curves important
To understand unique characteristics of mammalian ATP synthesis
What do simultaneous ADP and calcium experiments reveal
Calcium mitigates ADP-induced ΔΨm depolarization
How does ΔΨm behave in isolated mitochondria with no ADP
It remains hyperpolarized at approximately -170 mV
How can mitochondrial studies aid heart disease research
By identifying targets to enhance ATP production
What do findings about MCU suggest for drug development
Potential for targeting MCU to optimize cardiac energy metabolism
What can FRET-based tools measure in mitochondrial studies
Real-time calcium dynamics in cellular compartments
What is the relationship between workload and mitochondrial ATP production
ATP production increases with workload due to calcium-sensitive NADH generation
What is the role of ATP synthase in mitochondria
It synthesizes ATP using the proton gradient across the inner mitochondrial membrane
Why is the mitochondrial calcium uniporter important for cardiac function
It regulates calcium uptake into the mitochondria, crucial for ATP production
How do changes in cytosolic calcium affect mitochondrial calcium levels
Cytosolic calcium transients drive calcium influx into mitochondria via the MCU
What is the effect of workload on mitochondrial membrane potential
Workload increases the demand for ATP, maintaining ΔΨm through NADH production
How does calcium enhance ATP production during increased workload
Calcium activates dehydrogenases that boost NADH production, sustaining ΔΨm
What is the significance of studying calcium dynamics in cardiomyocytes
It helps understand energy production and signaling mechanisms critical for heart health
