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Cover Image
Cover Image
Cover picture: Minimum state diagram required to reproduce Na/K pump current-voltage relations, charge movements, and current decay in whole-cell recordings. E1 configurations bind instantaneously 3 Na or 2 K from the cytoplasmic side. Equivalent reactions in E2 configurations are all electrogenic and must be simulated kinetically. Pumps enter long-lived inactive states from E1 states with recovery being promoted by cytoplasmic Na binding. This composite function promotes tight control of the cytoplasmic Na concentration (see Research Article by Lu and Hilgemann, 727–749).
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Research News
Many parts make a whole: Calcium transients sum for slow waves
New JGP study shows how calcium events drive long intestinal slow wave plateaus.
Commentary
No fuzzy space for intracellular Na+ in healthy ventricular myocytes
Sachse et al. highlight work that reveals a Na+-dependent inactivation mechanism in the Na+/K+ pump.
Article
Elevated cAMP improves signal-to-noise ratio in amphibian rod photoreceptors
Vertebrate photoreceptors need to distinguish light signals from background noise to convey visual information to downstream bipolar cells. By affecting both signal and noise, Astakhova et al. find that increases in intracellular cAMP can improve the signal-to-noise ratio by twofold.
Clustering of Ca2+ transients in interstitial cells of Cajal defines slow wave duration
Electrical slow waves in the small intestine are generated by pacemaker cells called interstitial cells of Cajal. Drumm et al. record clusters of Ca2+ transients in these cells that are entrained by voltage-dependent Ca2+ entry and which define the duration of the electrical slow waves.
Na/K pump inactivation, subsarcolemmal Na measurements, and cytoplasmic ion turnover kinetics contradict restricted Na spaces in murine cardiac myocytes
The Na/K pump exports cytoplasmic Na ions while importing K ions, and its activity is thought to be affected by restricted intracellular Na diffusion in cardiac myocytes. Lu and Hilgemann find instead that the pump can enter an inactivated state and that inactivation can be relieved by cytoplasmic Na.
