title: MATLAB implementation of a dynamic clamp with bandwidth of >125 kHz capable of generating I Na at 37 °C.
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.
authors.affiliation: Department of Physiology and Biophysics and Institute for Molecular Cardiology, Health Sciences Center, Stony Brook University, Stony Brook, NY 11794-8661, USA. chris.clausen@stonybrook.edu
authors.forename: Chris
authors.initials: C
authors.lastname: Clausen
authors.forename: Virginijus
authors.initials: V
authors.lastname: Valiunas
authors.forename: Peter R
authors.initials: PR
authors.lastname: Brink
authors.forename: Ira S
authors.initials: IS
authors.lastname: Cohen
mesh_terms: D000200:Action Potentials; D000465:Algorithms; D057809:HEK293 Cells; D006358:Hot Temperature; D006801:Humans; D017136:Ion Transport; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques / Q000379:methods*; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*
chemical_list: D012964:Sodium; D011188:Potassium