[Frontiers in Bioscience 10, 905-918, January 1, 2005] 905 USE OF Mg AND Ca MACROELECTRODES TO MEASURE BINDING IN EXTRACELLULAR-LIKE PHYSIOLOGICAL SOLUTIONS

1. Abstract 2. Introduction 3. Materials and methods 3.1. Macroelectrodes 3.2. Experimental set-up/Recording 3.3. Solutions 3.3.1. Background solutions 3.3.2. Calibration solutions 3.3.3. Pipettes 3.4. Temperature 3.5. Macroelectrode calibration 3.6 Titration experiments 3.6.1. Titration of background solution 3.6.2. Titration of background solution containing organic anions 4. Results 4.1. Macroelectrodes 4.1.1. Drift 4.1.2. Comparison between the two methods of calibration 4.1.3. Reproducibility 4.1.4. Extension of calibration to lower concentration values 4.2. Magnesium binding studies 4.2.1. Aspartate 4.2.2. Malate 4.2.3. Citrate 4.3. Calcium binding studies 4.3.1. Malate 5. Discussion 5.1. Accuracy of the method 5.1.1. General accuracy 5.1.2. Extension of calibration to lower concentration values 5.2. Background contamination 5.3. Binding of Mg and Ca to organic anions. 5.3.1. Comparison between calculated and measured Kapp values 5.3.2. Biological relevance of the binding 5.4. Summary 6. Acknowledgements 7. References 8. Appendix 8.1. Definitions 8.2. Apparent concentration changes due to drift 8.3. Cation binding to anions 8.3.1. Binding of one cation 8.3.2. Binding of two cations