Abstract
We describe the construction of a dynamic clamp with a bandwidth of >125 kHz that utilizes a high-performance, yet low-cost, standard home/office PC interfaced with a high-speed (16 bit) data acquisition module. High bandwidth is achieved by exploiting recently available software advances (code-generation technology and optimized real-time kernel). Dynamic-clamp programs are constructed using Simulink, a visual programming language. Blocks for computation of membrane currents are written in the high-level MATLAB language; no programming in C is required. The instrument can be used in single- or dual-cell configurations, with the capability to modify programs while experiments are in progress. We describe an algorithm for computing the fast transient Na+ current (I Na) in real time and test its accuracy and stability using rate constants appropriate for 37 °C. We then construct a program capable of supplying three currents to a cell preparation: I Na, the hyperpolarizing-activated inward pacemaker current (I f) and an inward-rectifier K+ current (I K1). The program corrects for the IR drop due to electrode current flow and also records all voltages and currents. We tested this program on dual patch-clamped HEK293 cells where the dynamic clamp controls a current-clamp amplifier and a voltage-clamp amplifier controls membrane potential, and current-clamped HEK293 cells where the dynamic clamp produces spontaneous pacing behavior exhibiting Na+ spikes in otherwise passive cells.
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Acknowledgments
Mr. Robert Butz provided valuable hardware advice and built the dynamic clamp hardware. Dr. Michael R. Rosen provided critical comments on the manuscript. The xPC Target development team at Mathworks graciously responded to detailed technical questions regarding their xPC target software. This study is supported by the National Institutes of General Medical Sciences grant GM-088181; National Heart, Lung and Blood Institute grants HL-111401, HL-094410, and HL-111649; and New York Stem Cell Science grant CO24344.
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Clausen, C., Valiunas, V., Brink, P.R. et al. MATLAB implementation of a dynamic clamp with bandwidth of >125 kHz capable of generating I Na at 37 °C. Pflugers Arch - Eur J Physiol 465, 497–507 (2013). https://doi.org/10.1007/s00424-012-1186-8
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DOI: https://doi.org/10.1007/s00424-012-1186-8