Measurement of cytosolic calcium: ion selective microelectrodes.
Since the Ca2+-selective neutral carrier was introduced in 1972, Ca2+-selective microelectrodes have been made and used for measurement of Ca2+ activity (effective Ca2+ concentration) in the cytoplasm. Over the last several years, application of the technique has provided valuable information about resting levels and changes of cytosolic Ca2+ activity. This article reviews technical aspects of the electrodes, including their construction, calibration, and determination of cytosolic Ca2+ activity. The Ca2+-selective microelectrodes successfully prepared show the voltage responses of about 20 mV between 10(-6) and 10(-7) M Ca2+, and about 10 mV between 10(-7) and 10(-8) M Ca2+ so that they could be used to monitor changes in cytosolic free Ca2+. However, the techniques of the electrodes are still difficult as compared with those of other ion-selective microelectrodes. Some advantages and disadvantages of the techniques are discussed.
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Department of Physiology and Biophysics, Cornell University Medical College, New York, N.Y.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004867:Equipment Design; D008564:Membrane Potentials; D008839:Microelectrodes
D002118:Calcium