Achieving synaptically relevant pulses of neurotransmitter using PDMS microfluidics

• Published in: Journal of neuroscience methods 2009-03, Vol.177 (2), p.294-302
• Main Authors: Botzolakis, E.J., Maheshwari, A., Feng, H.J., Lagrange, A.H., Shaver, J.H., Kassebaum, N.J., Venkataraman, R., Baudenbacher, F., Macdonald, R.L.
• Format: Article
• Language: English
• Subjects: Allosteric Regulation - drug effects; Allosteric Regulation - physiology; Cell Line; Cys-loop; Drug Delivery Systems - instrumentation; Drug Delivery Systems - methods; Electronics, Medical - instrumentation; Electronics, Medical - methods; Electrophysiology; Electrophysiology - instrumentation; Electrophysiology - methods; GABAA receptor; Humans; Inhibitory Postsynaptic Potentials - drug effects; Inhibitory Postsynaptic Potentials - physiology; Ion channel; Kinetics; Ligand-gated; Microfluidic Analytical Techniques - instrumentation; Microfluidic Analytical Techniques - methods; Neural Inhibition - drug effects; Neural Inhibition - physiology; Neurochemistry - instrumentation; Neurochemistry - methods; Neurotransmitter Agents - metabolism; Neurotransmitter Agents - pharmacology; Neurotransmitter Agents - secretion; Patch clamp; Patch-Clamp Techniques - instrumentation; Patch-Clamp Techniques - methods; Pharmacology; Photolithography; Presynaptic Terminals - drug effects; Presynaptic Terminals - metabolism; Presynaptic Terminals - secretion; Receptors, GABA-A - drug effects; Receptors, GABA-A - metabolism; Recombinant Proteins - drug effects; Recombinant Proteins - metabolism; Solution exchange; Solution switching; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; Time Factors
• ISSN: 0165-0270; 1872-678X
• DOI: 10.1016/j.jneumeth.2008.10.014

Fast synaptic transmission is mediated by post-synaptic ligand-gated ion channels (LGICs) transiently activated by neurotransmitter released from pre-synaptic vesicles. Although disruption of synaptic transmission has been implicated in numerous neurological and psychiatric disorders, effective and practical methods for studying LGICs in vitro under synaptically relevant conditions are unavailable. Here, we describe a novel microfluidic approach to solution switching that allows for precise temporal control over the neurotransmitter transient while substantially increasing experimental throughput, flexibility, reproducibility, and cost-effectiveness. When this system was used to apply ultra-brief (∼400μs) GABA pulses to recombinant GABAA receptors, members of the cys-loop family of LGICs, the resulting currents resembled hippocampal inhibitory post-synaptic currents (IPSCs) and differed from currents evoked by longer, conventional pulses, illustrating the importance of evaluating LGICs on a synaptic timescale. This methodology should therefore allow the effects of disease-causing mutations and allosteric modulators to be evaluated in vitro under physiologically relevant conditions.