Fluorescence imaging of intracellular Ca2+

Area of Science:

• Cellular Biology
• Biochemistry
• Physiology

Background:

• Intracellular calcium concentrations ([Ca2+]i) are critical regulators of numerous cellular functions.
• Fura-2 is a sensitive and specific fluorescent indicator for measuring [Ca2+]i, allowing for minimal disruption to cell function.
• Fura-2's excitation wavelength shifts upon Ca2+ binding, enabling Ca2+ concentration estimation independent of dye concentration and cell thickness.

Purpose of the Study:

• To highlight the importance of measuring intracellular calcium concentrations ([Ca2+]i).
• To discuss the utility and limitations of the fluorescent indicator fura-2 for [Ca2+]i measurement.
• To explore the potential and challenges of quantitative fluorescence microscopy in studying intracellular calcium dynamics.

Main Methods:

• Utilizing the fluorescent indicator fura-2 for measuring intracellular calcium ([Ca2+]i).
• Employing fura-2 acetoxymethyl ester (AM) for cell membrane permeability.
• Applying quantitative fluorescence microscopy with low-light-level cameras and digital image processing.

Main Results:

• Quantitative fluorescence microscopy revealed significant spatial heterogeneity of [Ca2+]i across various cell types.
• New insights into dynamic intracellular biochemistry and signal transduction pathways were obtained.
• Identified limitations in current fura-2 based imaging technology, including dye properties and instrumentation.

Conclusions:

• Accurate measurement of intracellular calcium ([Ca2+]i) is essential for understanding cell signaling.
• Fura-2 is a valuable tool, but challenges like compartmentation and deesterification exist.
• Advancements in imaging techniques and novel probes are necessary to enhance temporal and spatial resolution for [Ca2+]i studies.