A Modified Coaxial Compound Micropipette for Extracellular Iontophoresis and Intracellular Recording: Fabrication, Performance and Theory

The Japanese Journal of Pharmacology

John E. Remmers²  Akira Haji¹  Jacqueline Wallace²  Ryuji Takeda¹  Stanley A. Schultz² 

[1] Department of Pharmacology, Faculty of Medicine, Toyama Medical and Pharmaceutical University;Respiratory Research Group, University of Calgary, Calgary

关键词: Transport number;    Brief pulse application;    Diffusional distance;    Membrane potential;    Iontophoresis;   

DOI  :  10.1254/jjp.75.161

学科分类：药理学

来源: Nihon Yakuri Gakkai Henshuubu / Japanese Pharmacological Society

【 摘 要 】

References(19)Cited-By(3)Investigation of the identity and modes of action of neurotransmitters in the mammalian central nervous system can be facilitated by simultaneous intracellular recording of membrane potential and extracellular iontophoresis of agonists and antagonists. We describe here techniques for conveniently constructing a compound microelectrode, originally described by Sonnhof (Pflugers Arch 341, 351-358, 1973), suitable for such studies. The Sonnhof electrode consists of two components, a centraxial micropipette for recording membrane potential surrounded by a cylindrical array of 6 pipettes for iontophoresis. The cylindrical array tapers coaxially and terminates in 6 contiguous, crescent-shaped orifices surrounding the terminal portion of the central pipette, 25-50 μm from the tip. Pipettes were constructed from borosilicate glass tubing of 1-mm wall thickness having a 10-mm or 16-mm outer diameter. The resistances, flux and transport numbers for iontophoresis of glycine were measured for pipettes constructed from both sizes of glass. Flux increased with increasing levels of current, and transport number decreased with increasing micropipette resistance. A spherical diffusion model points out the steep dependence of steady state concentration on diffusional distance, stressing the importance of diminishing the distance between the iontophoresis source and the recording site. This is particularly true when brief pulses of current are used.

【 授权许可】

Unknown