%0 Journal Article %1 Shan_1997_1524 %A Shannon, T. R. %A Bers, D. M. %D 1997 %J Biophys. J. %K 9284319 ATPase, Adenosine Animals, Calcium, Calorimetry, Fluorescence, Heart Kinetics, Microsomes, Myocardium, Rats, Reticulum, Sarcoplasmic Spectrometry, Sprague-Dawley, Thermodynamics, Triphosphate, Ventricles, {C}a$^{2+}$-Transporting %N 3 %P 1524--1531 %T Assessment of intra-SR free Ca and buffering in rat heart. %U http://www.pubmedcentral.gov/articlerender.fcgi?tool=pubmed&pubmedid=9284319 %V 73 %X To measure the free intrasarcoplasmic reticulum Ca (CaSR) in isolated rat cardiac microsomes, ventricular tissue was homogenized in the presence of the low-affinity Ca indicator furaptra. Stepwise increases in cuvette Ca (Cac) in the presence of ATP caused progressive increases in steady-state intravesicular fluorescence ratio to a maximum (Rmax). Steady-state CaSR/Cac was approximately 7000. Therefore the resting CaSR may approach 700 microM in the rat cardiac myocyte at Cac = 100 nM. The sarcoplasmic reticulum (SR) Ca pump requires a free energy of deltaG approximately 44 kJ x mol(-1) to generate this Ca gradient (e.g., approximately 74\% of deltaG(ATP)). Total SR 45Ca uptake was also measured in digitonin-permeabilized myocytes as a function of Cac in the absence of precipitating ions. The steady-state SR Ca content at 100 nM Cac was approximately 400 micromol/liter cytosolic volume. Used together, these data allowed evaluation of the in situ SR Ca-buffering properties. The SR Ca-binding site concentration was approximately 14 mM, and Kd(Ca) approximately 0.638 mM CaSR.

@article{Shan_1997_1524, abstract = {To measure the free intrasarcoplasmic reticulum [Ca] ([Ca]SR) in isolated rat cardiac microsomes, ventricular tissue was homogenized in the presence of the low-affinity Ca indicator furaptra. Stepwise increases in cuvette [Ca] ([Ca]c) in the presence of ATP caused progressive increases in steady-state intravesicular fluorescence ratio to a maximum (Rmax). Steady-state [Ca]SR/[Ca]c was approximately 7000. Therefore the resting [Ca]SR may approach 700 microM in the rat cardiac myocyte at [Ca]c = 100 nM. The sarcoplasmic reticulum (SR) Ca pump requires a free energy of deltaG approximately 44 kJ x mol(-1) to generate this [Ca] gradient (e.g., approximately 74\% of deltaG(ATP)). Total SR 45Ca uptake was also measured in digitonin-permeabilized myocytes as a function of [Ca]c in the absence of precipitating ions. The steady-state SR Ca content at 100 nM [Ca]c was approximately 400 micromol/liter cytosolic volume. Used together, these data allowed evaluation of the in situ SR Ca-buffering properties. The SR Ca-binding site concentration was approximately 14 mM, and Kd(Ca) approximately 0.638 mM [Ca]SR.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Shannon, T. R. and Bers, D. M.}, biburl = {https://www.bibsonomy.org/bibtex/2cfd37731535f9a1b2bb0b614ca623b73/hake}, description = {The whole bibliography file I use.}, file = {Shan_1997_1524.pdf:Shan_1997_1524.pdf:PDF}, interhash = {1675e9e354efb662e4037a25053d4178}, intrahash = {cfd37731535f9a1b2bb0b614ca623b73}, journal = {Biophys. J.}, key = 267, keywords = {9284319 ATPase, Adenosine Animals, Calcium, Calorimetry, Fluorescence, Heart Kinetics, Microsomes, Myocardium, Rats, Reticulum, Sarcoplasmic Spectrometry, Sprague-Dawley, Thermodynamics, Triphosphate, Ventricles, {C}a$^{2+}$-Transporting}, month = Sep, number = 3, pages = {1524--1531}, pmid = {9284319}, timestamp = {2009-06-03T11:21:29.000+0200}, title = {Assessment of intra-SR free [Ca] and buffering in rat heart.}, url = {http://www.pubmedcentral.gov/articlerender.fcgi?tool=pubmed&pubmedid=9284319}, volume = 73, year = 1997 }