%0 Journal Article %1 Traf_1995_577 %A Trafford, A. W. %A D�az, M. E. %A O'Neill, S. C. %A Eisner, D. A. %D 1995 %J J. Physiol. %K 8576849 Animals, Biological Calcium, Cell Comparative Compartmentation, Dyes, Fluorescent Gov't, Heart Indoles, Myocardium, Non-U.S. Patch-Clamp Rats, Research Sarcolemma, Study, Support, Techniques, Transport, Ventricles, %P 577--586 %T Comparison of subsarcolemmal and bulk calcium concentration during spontaneous calcium release in rat ventricular myocytes. %U http://jp.physoc.org/cgi/content/abstract/488/3/577 %V 488 ( Pt 3) %X 1. The aim of these experiments was to compare the time course of changes in intracellular Ca$^2+$ concentration (Ca$^2+$i) measured in the bulk cytoplasm with those estimated to occur near the sarcolemma. Sarcolemmal Na$^+$-Ca$^2+$ exchange current and Ca$^2+$i were measured in single, voltage-clamped ventricular myocytes. 2. Spontaneous Ca$^2+$ release from the sarcoplasmic reticulum (SR) resulted in a transient inward current. This current developed and decayed more quickly than the accompanying changes in Ca$^2+$i (measured with indo-1) resulting in a hysteresis between Ca$^2+$i and current. A similar hysteresis was also observed if Ca$^2+$i was elevated with caffeine and was removed if the current was low pass filtered with a time constant of 132 ms. 3. Digital video imaging (using fluo-3 or calcium green-1 to measure Ca$^2+$i) allowed measurement of Ca$^2+$i at all points in the cell during the wave of spontaneous Ca$^2+$ release. The hysteresis between Ca$^2+$i and current remained, even after allowing for the spatial and temporal properties of this wave. 4. The hysteresis can be accounted for if there is a barrier to diffusion of Ca$^2+$ ions separating the bulk cytoplasm from the space under the sarcolemma (into which Ca$^2+$ is released from the sarcoplasmic reticulum). The calculated subsarcolemmal Ca$^2+$ rises and falls more quickly (and reaches a higher peak) than does the bulk Ca$^2+$. The delay introduced by this barrier is equivalent to a time constant of 133 ms. 5. The subsarcolemmal space described in this paper may be equivalent to the 'fuzzy space' previously suggested to be important in controlling SR Ca$^2+$ release.

@article{Traf_1995_577, abstract = {1. The aim of these experiments was to compare the time course of changes in intracellular {C}a$^{2+}$ concentration ([{C}a$^{2+}$]i) measured in the bulk cytoplasm with those estimated to occur near the sarcolemma. Sarcolemmal {N}a$^{+}$-{C}a$^{2+}$ exchange current and [{C}a$^{2+}$]i were measured in single, voltage-clamped ventricular myocytes. 2. Spontaneous {C}a$^{2+}$ release from the sarcoplasmic reticulum (SR) resulted in a transient inward current. This current developed and decayed more quickly than the accompanying changes in [{C}a$^{2+}$]i (measured with indo-1) resulting in a hysteresis between [{C}a$^{2+}$]i and current. A similar hysteresis was also observed if [{C}a$^{2+}$]i was elevated with caffeine and was removed if the current was low pass filtered with a time constant of 132 ms. 3. Digital video imaging (using fluo-3 or calcium green-1 to measure [{C}a$^{2+}$]i) allowed measurement of [{C}a$^{2+}$]i at all points in the cell during the wave of spontaneous {C}a$^{2+}$ release. The hysteresis between [{C}a$^{2+}$]i and current remained, even after allowing for the spatial and temporal properties of this wave. 4. The hysteresis can be accounted for if there is a barrier to diffusion of {C}a$^{2+}$ ions separating the bulk cytoplasm from the space under the sarcolemma (into which {C}a$^{2+}$ is released from the sarcoplasmic reticulum). The calculated subsarcolemmal [{C}a$^{2+}$] rises and falls more quickly (and reaches a higher peak) than does the bulk [{C}a$^{2+}$]. The delay introduced by this barrier is equivalent to a time constant of 133 ms. 5. The subsarcolemmal space described in this paper may be equivalent to the 'fuzzy space' previously suggested to be important in controlling SR {C}a$^{2+}$ release.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Trafford, A. W. and D�az, M. E. and O'Neill, S. C. and Eisner, D. A.}, biburl = {https://www.bibsonomy.org/bibtex/2ca059f19d1726dee2b5049ec98e504eb/hake}, description = {The whole bibliography file I use.}, interhash = {4c3112b3a2fc18498766369b88448d60}, intrahash = {ca059f19d1726dee2b5049ec98e504eb}, journal = {J. Physiol.}, keywords = {8576849 Animals, Biological Calcium, Cell Comparative Compartmentation, Dyes, Fluorescent Gov't, Heart Indoles, Myocardium, Non-U.S. Patch-Clamp Rats, Research Sarcolemma, Study, Support, Techniques, Transport, Ventricles,}, month = Nov, pages = {577--586}, pmid = {8576849}, timestamp = {2009-06-03T11:21:34.000+0200}, title = {Comparison of subsarcolemmal and bulk calcium concentration during spontaneous calcium release in rat ventricular myocytes.}, url = {http://jp.physoc.org/cgi/content/abstract/488/3/577}, volume = {488 ( Pt 3)}, year = 1995 }