%0 Journal Article %1 Fu_2005_2533 %A Fu, Yu %A Zhang, Guang-Qin %A Hao, Xue-Mei %A Wu, Cai-Hong %A Chai, Zhen %A Wang, Shi-Qiang %D 2005 %J Biophys. J. %K 16113119 %N 4 %P 2533--2541 %R 10.1529/biophysj.105.067074 %T Temperature dependence and thermodynamic properties of Ca$^2+$ sparks in rat cardiomyocytes. %U http://dx.doi.org/10.1529/biophysj.105.067074 %V 89 %X To elucidate the temperature dependence and underlying thermodynamic determinants of the elementary Ca$^2+$ release from the sarcoplasmic reticulum, we characterized Ca$^2+$ sparks originating from ryanodine receptors (RyRs) in rat cardiomyocytes over a wide range of temperature. From 35 degrees C to 10 degrees C, the normalized fluo-3 fluorescence of Ca$^2+$ sparks decreased monotonically, but the DeltaCa$^2+$(i) were relatively unchanged due to increased resting Ca$^2+$(i). The time-to-peak of Ca$^2+$ sparks, which represents the RyR Ca$^2+$ release duration, was prolonged by 37\% from 35 degrees C to 10 degrees C. An Arrhenius plot of the data identified a jump of apparent activation energy from 5.2 to 14.6 kJ/mol at 24.8 degrees C, which presumably reflects a transition of sarcoplasmic reticulum lipids. Thermodynamic analysis of the decay kinetics showed that active transport plays little role in early recovery but a significant role in late recovery of local Ca$^2+$ concentration. These results provided a basis for quantitative interpretation of intracellular Ca$^2+$ signaling under various thermal conditions. The relative temperature insensitivity above the transitional 25 degrees C led to the notion that Ca$^2+$ sparks measured at a "warm room" temperature are basically acceptable in elucidating mammalian heart function.

@article{Fu_2005_2533, abstract = {To elucidate the temperature dependence and underlying thermodynamic determinants of the elementary {C}a$^{2+}$ release from the sarcoplasmic reticulum, we characterized {C}a$^{2+}$ sparks originating from ryanodine receptors (RyRs) in rat cardiomyocytes over a wide range of temperature. From 35 degrees C to 10 degrees C, the normalized fluo-3 fluorescence of {C}a$^{2+}$ sparks decreased monotonically, but the Delta[{C}a$^{2+}$](i) were relatively unchanged due to increased resting [{C}a$^{2+}$](i). The time-to-peak of {C}a$^{2+}$ sparks, which represents the RyR {C}a$^{2+}$ release duration, was prolonged by 37\% from 35 degrees C to 10 degrees C. An Arrhenius plot of the data identified a jump of apparent activation energy from 5.2 to 14.6 kJ/mol at 24.8 degrees C, which presumably reflects a transition of sarcoplasmic reticulum lipids. Thermodynamic analysis of the decay kinetics showed that active transport plays little role in early recovery but a significant role in late recovery of local {C}a$^{2+}$ concentration. These results provided a basis for quantitative interpretation of intracellular {C}a$^{2+}$ signaling under various thermal conditions. The relative temperature insensitivity above the transitional 25 degrees C led to the notion that {C}a$^{2+}$ sparks measured at a "warm room" temperature are basically acceptable in elucidating mammalian heart function.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Fu, Yu and Zhang, Guang-Qin and Hao, Xue-Mei and Wu, Cai-Hong and Chai, Zhen and Wang, Shi-Qiang}, biburl = {https://www.bibsonomy.org/bibtex/2e194aac72a985489fa58f359193ee486/hake}, description = {The whole bibliography file I use.}, doi = {10.1529/biophysj.105.067074}, file = {Fu_2005_2533.pdf:Fu_2005_2533.pdf:PDF}, interhash = {380f6ee9a7ec3666812162eb51e6d903}, intrahash = {e194aac72a985489fa58f359193ee486}, journal = {Biophys. J.}, key = 161, keywords = {16113119}, month = Oct, number = 4, pages = {2533--2541}, pii = {biophysj.105.067074}, pmid = {16113119}, timestamp = {2009-06-03T11:21:12.000+0200}, title = {Temperature dependence and thermodynamic properties of {C}a$^{2+}$ sparks in rat cardiomyocytes.}, url = {http://dx.doi.org/10.1529/biophysj.105.067074}, volume = 89, year = 2005 }