A new dynamic model for non-Fickian diffu-sion of calcium spark in cardiac myocytes was developed by introducing time lags on the basis of the microscale mass transport theory. Numerical simulation showed that the siz...A new dynamic model for non-Fickian diffu-sion of calcium spark in cardiac myocytes was developed by introducing time lags on the basis of the microscale mass transport theory. Numerical simulation showed that the size of the calcium spark produced by the new dynamic model was larger than that of Fick diffusion and was in more agreement with experimental results. In addition, the time lags of the calcium spark in cardiac myocytes were about 0.1—0.8 ms. These results can be used to understand the mechanism of calcium spark diffusion in cardiac myocytes.展开更多
With a new fluorescence probe of Ca2+, STDIn-AM, 5-hydroxytryptamino (5-HT)-induced spontaneous calcium release events (calcium sparks) in cultured rat stomach fundus smooth mus-cle cells (SFSMC) are investigated by l...With a new fluorescence probe of Ca2+, STDIn-AM, 5-hydroxytryptamino (5-HT)-induced spontaneous calcium release events (calcium sparks) in cultured rat stomach fundus smooth mus-cle cells (SFSMC) are investigated by laser scanning confocal microscope. The mechanisms of initiation of Ca2+ sparks, propagating Ca2+ waves and their relation to E-C coupling are discussed. After the extracellular [Ca2+] is increased to 10 mmol/L, addition of 5-HT causes hot spots throughout the cytoplasm, which is brighter near the plasmalemma. The amplitude of the event is at least two times greater than the standard deviation of fluorescence intensity fluctuations meas-ured in the neighboring region and the duration of the Ca2+ signal is over 100 ms. The results sug-gest that 5-HT acts by the way of 5-HT2 receptors on SFSMC, then through 5-HT2 receptors cou-ples IP3/Ca2+ and DG/PKC double signal transduction pathways to cause Ca2+ release from intra-cellular Ca2+ stores and followed Ca2+ influx possibly through calcium release-activated calcium influx. The acceptor of activated 5-HT2 can also cause membrane depolarization, which then stimulates the L-type Ca2+ channels leading to Ca2+ influx. Then the local Ca2+ entry mentioned above activates ryanodine-sensitive Ca2+ release channels (RyR) on sarcoplasmic reticulum (SR) to cause local Ca2+ release events (Ca2+ sparks) through calcium-induced calcium release (CICR).展开更多
Calcium release from sarcoplasmic reticulum (SR) though Ryanodine receptors plays an important role in excitation contraction coupling of cardiac myocytes. This
基金supported by the National Natural Science Foundation of China(Grant No.10372007)Bio-x center of Peking University and Japan Society for the Promotion of Science(PO2325).
文摘A new dynamic model for non-Fickian diffu-sion of calcium spark in cardiac myocytes was developed by introducing time lags on the basis of the microscale mass transport theory. Numerical simulation showed that the size of the calcium spark produced by the new dynamic model was larger than that of Fick diffusion and was in more agreement with experimental results. In addition, the time lags of the calcium spark in cardiac myocytes were about 0.1—0.8 ms. These results can be used to understand the mechanism of calcium spark diffusion in cardiac myocytes.
文摘With a new fluorescence probe of Ca2+, STDIn-AM, 5-hydroxytryptamino (5-HT)-induced spontaneous calcium release events (calcium sparks) in cultured rat stomach fundus smooth mus-cle cells (SFSMC) are investigated by laser scanning confocal microscope. The mechanisms of initiation of Ca2+ sparks, propagating Ca2+ waves and their relation to E-C coupling are discussed. After the extracellular [Ca2+] is increased to 10 mmol/L, addition of 5-HT causes hot spots throughout the cytoplasm, which is brighter near the plasmalemma. The amplitude of the event is at least two times greater than the standard deviation of fluorescence intensity fluctuations meas-ured in the neighboring region and the duration of the Ca2+ signal is over 100 ms. The results sug-gest that 5-HT acts by the way of 5-HT2 receptors on SFSMC, then through 5-HT2 receptors cou-ples IP3/Ca2+ and DG/PKC double signal transduction pathways to cause Ca2+ release from intra-cellular Ca2+ stores and followed Ca2+ influx possibly through calcium release-activated calcium influx. The acceptor of activated 5-HT2 can also cause membrane depolarization, which then stimulates the L-type Ca2+ channels leading to Ca2+ influx. Then the local Ca2+ entry mentioned above activates ryanodine-sensitive Ca2+ release channels (RyR) on sarcoplasmic reticulum (SR) to cause local Ca2+ release events (Ca2+ sparks) through calcium-induced calcium release (CICR).
文摘Calcium release from sarcoplasmic reticulum (SR) though Ryanodine receptors plays an important role in excitation contraction coupling of cardiac myocytes. This
