Proper use of DM-nitrophen.
If anyone is interested in seeing DM-nitrophen used in a quantitative study, then read the very elegant paper by Bollmann & Sakmann in Nature Neuroscience last year (2005, 8: 426-434; doi:10.1038/nm1417).
One of the Holy Grails of synaptic physiology is the quantitative correlation of presynaptic calcium concentration with postsynaptic currents. The calcium microdomains that drive secretion are too fast and small to image, so a few years ago the Neher and Sakmann groups resorted to a roundabout means to get at this using calcium uncaging from DM-nitrophen and NP-EGTA (Nature (2000) 406: 889-893; Science (2000) 289: 953-957). Both groups used the calyx of Held, as it is sufficiently large and robust to allow double patching of pre and postsynaptic cells. Global uncaging of calcium throughout the presynaptic cell produced a sustained elevation in calcium that can be measured. (I remember when I first met Gerrard Borst as a postdoc in Heidelberg, he told me he was happy if he got 3 pairs a week! I can only assume the success rate has gone up since then, as Bollmann a mind-boggling amount of data.) Bollmann filled many presynaptic cells with various proportions of DM-nitrophen, calcium, oregon green BAPTA-5N and buffer (EGTA or BAPTA). These cocktails permit different calcium concentration waveforms to be generated in a reproducible and quantitative manner by uncaging from DM-nitrophen. (A Nd:YAG laser was used for uncaging; pulse-width 3 ns.) In the great tradition of Hodgkin and Huxley, Bollmann also produced a model of the dependence of postsynaptic current upon the occupany of calcium on the secretory machinery to account for his data, and predict rise times of [calcium] vs. postsynaptic current and explain superlinear amplification during paired-pulse facilitation. A proper use of DM-nitrophen indeed!
If anyone is interested in seeing DM-nitrophen used in a quantitative study, then read the very elegant paper by Bollmann & Sakmann in Nature Neuroscience last year (2005, 8: 426-434; doi:10.1038/nm1417).
One of the Holy Grails of synaptic physiology is the quantitative correlation of presynaptic calcium concentration with postsynaptic currents. The calcium microdomains that drive secretion are too fast and small to image, so a few years ago the Neher and Sakmann groups resorted to a roundabout means to get at this using calcium uncaging from DM-nitrophen and NP-EGTA (Nature (2000) 406: 889-893; Science (2000) 289: 953-957). Both groups used the calyx of Held, as it is sufficiently large and robust to allow double patching of pre and postsynaptic cells. Global uncaging of calcium throughout the presynaptic cell produced a sustained elevation in calcium that can be measured. (I remember when I first met Gerrard Borst as a postdoc in Heidelberg, he told me he was happy if he got 3 pairs a week! I can only assume the success rate has gone up since then, as Bollmann a mind-boggling amount of data.) Bollmann filled many presynaptic cells with various proportions of DM-nitrophen, calcium, oregon green BAPTA-5N and buffer (EGTA or BAPTA). These cocktails permit different calcium concentration waveforms to be generated in a reproducible and quantitative manner by uncaging from DM-nitrophen. (A Nd:YAG laser was used for uncaging; pulse-width 3 ns.) In the great tradition of Hodgkin and Huxley, Bollmann also produced a model of the dependence of postsynaptic current upon the occupany of calcium on the secretory machinery to account for his data, and predict rise times of [calcium] vs. postsynaptic current and explain superlinear amplification during paired-pulse facilitation. A proper use of DM-nitrophen indeed!
posted by graham at 8:23 AM
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