%0 Journal Article %1 Pesk_1992_59 %A Peskoff, A. %A Post, J. A. %A Langer, G. A. %D 1992 %J J. Membr. Biol. %K 1404341 Animals, Binding Calcium, Cell Cells, Compartmentation, Cultured, Gov't, Lanthanum, Models, Myocardium, Newborn, Nifedipine, Non-U.S. P.H.S., Rats, Research Reticulu, Ryanodine, Sarcolemma, Sarcoplasmic Sites, Support, Terpenes, Thapsigargin, Theoretical, U.S. m, %N 1 %P 59--69 %R 10.1007/BF00232055 %T Sarcolemmal calcium binding sites in heart: II. Mathematical model for diffusion of calcium released from the sarcoplasmic reticulum into the diadic region. %U http://dx.doi.org/10.1007/BF00232055 %V 129 %X We present a model for predicting the temporal and spatial dependence of Ca in the cardiac subsarcolemmal diadic region (cleft), following Ca release from the "feet" of the sarcoplasmic reticulum. This region is modeled as a disc 10 nm thick, 430 nm in radius, with or without Ca binding sites and open at its periphery to the cytosol. Ca is computed for three diffusion coefficients (100, 20 and 4\% of aqueous diffusion), following release of a 20-msec square pulse sufficient to produce 50\% maximal contractile force, or repetitive release (400/min) of such pulses. Numerical solutions are obtained for the general diffusion/binding problem and analytic solutions for the case of no binding sites. For the middle value of diffusion coefficient, and in the absence of binding sites, Ca rises to approximately 1.5 mM in 20-msec and then falls to approximately 0.1 microM in less than 3 msec. Adding binding sites reduces peak Ca to approximately 0.6 mM but prolongs its decline, requiring approximately 200 msec to reach 20 microM. For repetitive release Ca is greater than 100 microM for roughly half of each cycle. Two major implications of the predicted Ca are: (i) The effect of Ca binding sites on Ca will cause Ca efflux from the cleft via the Na-Ca exchanger (Km(Ca) approximately 20 microM) to continue at a significant level for greater than 200 msec. (ii) The time constant for inactivation of release from the "feet" must be much greater than for activation if Ca-induced Ca release is to continue for greater than 1-2 msec.

@article{Pesk_1992_59, abstract = {We present a model for predicting the temporal and spatial dependence of [Ca] in the cardiac subsarcolemmal diadic region (cleft), following Ca release from the "feet" of the sarcoplasmic reticulum. This region is modeled as a disc 10 nm thick, 430 nm in radius, with or without Ca binding sites and open at its periphery to the cytosol. [Ca] is computed for three diffusion coefficients (100, 20 and 4\% of aqueous diffusion), following release of a 20-msec square pulse sufficient to produce 50\% maximal contractile force, or repetitive release (400/min) of such pulses. Numerical solutions are obtained for the general diffusion/binding problem and analytic solutions for the case of no binding sites. For the middle value of diffusion coefficient, and in the absence of binding sites, [Ca] rises to approximately 1.5 mM in 20-msec and then falls to approximately 0.1 microM in less than 3 msec. Adding binding sites reduces peak [Ca] to approximately 0.6 mM but prolongs its decline, requiring approximately 200 msec to reach 20 microM. For repetitive release [Ca] is greater than 100 microM for roughly half of each cycle. Two major implications of the predicted [Ca] are: (i) The effect of Ca binding sites on [Ca] will cause Ca efflux from the cleft via the Na-Ca exchanger (Km(Ca) approximately 20 microM) to continue at a significant level for greater than 200 msec. (ii) The time constant for inactivation of release from the "feet" must be much greater than for activation if Ca-induced Ca release is to continue for greater than 1-2 msec.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Peskoff, A. and Post, J. A. and Langer, G. A.}, biburl = {https://www.bibsonomy.org/bibtex/28906d23bae9029756b58ef6c69bcd9a2/hake}, description = {The whole bibliography file I use.}, doi = {10.1007/BF00232055}, file = {Pesk_1992_59.pdf:Pesk_1992_59.pdf:PDF}, interhash = {ff8b8732fe968531c83e7e1700fc80b2}, intrahash = {8906d23bae9029756b58ef6c69bcd9a2}, journal = {J. Membr. Biol.}, key = 236, keywords = {1404341 Animals, Binding Calcium, Cell Cells, Compartmentation, Cultured, Gov't, Lanthanum, Models, Myocardium, Newborn, Nifedipine, Non-U.S. P.H.S., Rats, Research Reticulu, Ryanodine, Sarcolemma, Sarcoplasmic Sites, Support, Terpenes, Thapsigargin, Theoretical, U.S. m,}, month = Jul, number = 1, pages = {59--69}, pmid = {1404341}, timestamp = {2009-06-03T11:21:25.000+0200}, title = {Sarcolemmal calcium binding sites in heart: {II}. Mathematical model for diffusion of calcium released from the sarcoplasmic reticulum into the diadic region.}, url = {http://dx.doi.org/10.1007/BF00232055}, volume = 129, year = 1992 }