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Rates of diffusional exchange between small cells and a measuring patch pipette.
1Max-Planck-Institut für biophysikalische Chemie, Göttingen, Federal Republic of Germany.
Pflugers Archiv : European Journal of Physiology
|February 1, 1988
Summary
This study quantifies diffusion rates between patch pipettes and cells using fluorescent compounds and ion currents. Results reveal diffusion time constants depend on pipette access resistance and cell size, crucial for patch clamp technique optimization.
Area of Science:
- Biophysics
- Cellular Physiology
Background:
- The patch clamp technique is vital for studying ion channel function.
- Accurate measurement of intracellular concentrations is essential for interpreting patch clamp data.
Purpose of the Study:
- To investigate the kinetics of diffusional exchange between cells and patch pipettes.
- To determine factors influencing intracellular substance concentration changes during patch clamp experiments.
Main Methods:
- Utilized fluorescent compounds and ion currents (Na+, K+) to monitor intracellular concentration changes.
- Employed the tight seal whole cell configuration of the patch clamp technique.
- Analyzed concentration changes using single exponential fits and related them to access resistance and cell size.
Main Results:
- Diffusion time constants were linearly related to pipette access resistance.
- Normalized diffusion rates depended on cell size, with cell capacitance not being a precise measure.
- Experimental diffusion rates correlated with diffusion coefficients and molecular weight.
Conclusions:
- Developed a method to estimate diffusion time constants for substances exchanged between patch pipettes and cytoplasm.
- Highlighted the importance of access resistance and cell size in patch clamp experiments.
- Provided a framework for optimizing experimental conditions for accurate intracellular studies.