Measurements of Intracellular Free Ca++
This manuscript reviews the work of this laboratory over the last six years in measuring, non-destructively and kinetically, ionized Ca++ in the cytosol of single resting cells and the changes in Ca++ following metabolic, electrical, and contractile events. The strategy of this study is to use Ca++ indicators with suitable selectivity and sensitivity, to inject them into the cytosol of large cells, and to measure with sensitive micro-spectrophotometry the absorbance of these indicators in situ as a function of Ca++ concentration. This approach, which essentially uses a large cell as a biological cuvet, has been successful both in large neurons and single large muscle cells. We will briefly review five areas: the characteristics of Ca++ metallochromic indicators; the experimental set-up to measure free cytosolic Ca++ in single cells; the measurement of free Ca++ in a resting cell; the kinetics of mitochondrial Ca++ uptake and release in single cells in situ; and the intracellular free Ca++ transients during contractile events in a single muscle cell.
KeywordsDual Wavelength Contractile Event Squid Giant Axon Squid Axon Wavelength Pair
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