%0 Journal Article %1 Reut_2003_19 %A Reuter, Hannes %A Henderson, Scott A %A Han, Tieyan %A Mottino, Giuliano A %A Frank, Joy S %A Ross, Robert S %A Goldhaber, Joshua I %A Philipson, Kenneth D %D 2003 %J Cell Calcium %K 12767889 ATPase, Action Adaptation, Animals, Blockers, Caffeine, Calcium Calcium, Cardiac, Channel Channels, Contraction, Culture Deletion, Echocardiography, Electron, Exchanger, Exons, Female, Fetal Fetus, Gene Gov't, Heart, Integrases, Intracellular Isoproterenol, Knockout, L-Type, Male, Membranes, Mice, Microscopy, Models, Molecular, Myocardial Myocardium, Myocytes, Non-U.S. Organ P.H.S., Patch-Clamp Physiological, Potentials, Proteins, Research Reticulum, Sarcoplasmic Sequence Signaling, Sodium, Sodium-Calcium Support, Targeting, Techniques, U.S. Viral {C}a$^{2+}$-Transporting %N 1 %P 19-26 %T Cardiac excitation-contraction coupling in the absence of Na$^+$ - Ca$^2+$ exchange. %U http://dx.doi.org/10.1016/S0143-4160(03)00018-6 %V 34 %X We investigate cardiac excitation-contraction coupling in the absence of sarcolemmal Na$^+$ - Ca$^2+$ exchange using NCX1 knock out mice. Knock out of NCX1 is embryonic lethal, and we measure Ca$^2+$ transients and contractions in heart tubes from embryos at day 9.5 post coitum. Immunoblot and electron microscopy both indicate that sarcoplasmic reticular membranes are diminished in the knock out (NCX(-/-)) heart tubes. Both Ni$^2+$ and nifedipine block excitation-contraction coupling in NCX-containing (NCX+) and NCX(-/-) heart tubes indicating an essential role for the L-type Ca$^2+$ current. Under basal conditions (1Hz stimulation), the NCX(-/-) heart tubes have normal Ca$^2+$ transients but are unable to maintain homeostasis when Ca$^2+$ fluxes are increased by various interventions (increased stimulation frequency, caffeine, isoproterenol). In each case, the NCX(-/-) heart tubes respond to the intervention in a more deleterious manner (increased diastolic Ca$^2+$, decreased Ca$^2+$ transient) than the NCX+ heart tubes. Expression of the sarcolemmal Ca$^2+$ pump was not upregulated. The sarcolemmal Ca$^2+$ pump, however, was able to compensate surprisingly well for the absence of Na$^+$ - Ca$^2+$ exchange under basal conditions.

@article{Reut_2003_19, abstract = {We investigate cardiac excitation-contraction coupling in the absence of sarcolemmal {N}a$^{+}$ - {C}a$^{2+}$ exchange using NCX1 knock out mice. Knock out of NCX1 is embryonic lethal, and we measure {C}a$^{2+}$ transients and contractions in heart tubes from embryos at day 9.5 post coitum. Immunoblot and electron microscopy both indicate that sarcoplasmic reticular membranes are diminished in the knock out (NCX(-/-)) heart tubes. Both {N}i$^{2+}$ and nifedipine block excitation-contraction coupling in NCX-containing (NCX+) and NCX(-/-) heart tubes indicating an essential role for the L-type {C}a$^{2+}$ current. Under basal conditions (1Hz stimulation), the NCX(-/-) heart tubes have normal {C}a$^{2+}$ transients but are unable to maintain homeostasis when {C}a$^{2+}$ fluxes are increased by various interventions (increased stimulation frequency, caffeine, isoproterenol). In each case, the NCX(-/-) heart tubes respond to the intervention in a more deleterious manner (increased diastolic {C}a$^{2+}$, decreased {C}a$^{2+}$ transient) than the NCX+ heart tubes. Expression of the sarcolemmal {C}a$^{2+}$ pump was not upregulated. The sarcolemmal {C}a$^{2+}$ pump, however, was able to compensate surprisingly well for the absence of {N}a$^{+}$ - {C}a$^{2+}$ exchange under basal conditions.}, added-at = {2009-06-03T11:20:58.000+0200}, author = {Reuter, Hannes and Henderson, Scott A and Han, Tieyan and Mottino, Giuliano A and Frank, Joy S and Ross, Robert S and Goldhaber, Joshua I and Philipson, Kenneth D}, biburl = {https://www.bibsonomy.org/bibtex/2c89a796b38a1875f93c78bfd87dc82e0/hake}, description = {The whole bibliography file I use.}, file = {Reut_2003_19.pdf:Reut_2003_19.pdf:PDF}, interhash = {6cba93655d27f3ee808aa9f9db727fc7}, intrahash = {c89a796b38a1875f93c78bfd87dc82e0}, journal = {Cell Calcium}, keywords = {12767889 ATPase, Action Adaptation, Animals, Blockers, Caffeine, Calcium Calcium, Cardiac, Channel Channels, Contraction, Culture Deletion, Echocardiography, Electron, Exchanger, Exons, Female, Fetal Fetus, Gene Gov't, Heart, Integrases, Intracellular Isoproterenol, Knockout, L-Type, Male, Membranes, Mice, Microscopy, Models, Molecular, Myocardial Myocardium, Myocytes, Non-U.S. Organ P.H.S., Patch-Clamp Physiological, Potentials, Proteins, Research Reticulum, Sarcoplasmic Sequence Signaling, Sodium, Sodium-Calcium Support, Targeting, Techniques, U.S. Viral {C}a$^{2+}$-Transporting}, month = Jul, number = 1, pages = {19-26}, pii = {S0143416003000186}, timestamp = {2009-06-03T11:21:26.000+0200}, title = {Cardiac excitation-contraction coupling in the absence of {N}a$^{+}$ - {C}a$^{2+}$ exchange.}, url = {http://dx.doi.org/10.1016/S0143-4160(03)00018-6}, volume = 34, year = 2003 }