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Dresden 2020 – scientific programme

The DPG Spring Meeting in Dresden had to be cancelled! Read more ...

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BP: Fachverband Biologische Physik

BP 31: Computational Biophysics (joint session BP/CPP)

BP 31.1: Talk

Thursday, March 19, 2020, 09:30–09:45, SCH A251

Effectiveness of Ca2+ clearance by PMCA pumps — •Barbara Schmidt1, Cristina Constantin2, Bernd Fakler2, and Heiko Rieger11Center for Biophysics and Department of Theoretical Physics, Saarland University, 66123 Saarbrücken, Germany — 2Institute of Physiology, University of Freiburg, 79104 Freiburg, Germany

Ca2+ influx through voltage-gated (Cav) channels leads to an increase in the intracellular Ca2+-concentration ([Ca2+]i) that can be monitored by BK-type Ca2+-activated K+ channels. Due to their gating kinetics they may be used as sensors for [Ca2+]i underneath the plasma membrane. Here, K+ currents through BK channels were used to determine the Ca2+ transport activity of Ca2+-ATPases of the plasma membrane (PMCA), the classical Ca2+ pumps. Experimentally we monitored PMCA-mediated Ca2+ clearance by the decay of BK-currents following their activation by a short (0.8 ms) period of Ca2+-influx through Cav2.2 channels. Our theoretical model describes the Ca2+ diffusion within a spherical cell. Time- and Ca2+ concentration-dependent boundary conditions model the initial Ca2+ influx and the following outflow via the PMCA pumps. The time scale of this diffusion process is used to predict the strength of the PMCA pumps. Based on the experimentally determined density of Cav channels and PMCA pumps within the membrane we predict a PMCA pump strength that is at least 1.5 orders of magnitude larger than what has been assumed so far.

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