Optimization of a multi-channel puffer system for rapid delivery of solutions during patch-clamp experiments

In biological experiments, especially in neuroscience research, it is important to manipulate the extracellular environment efficiently. We have developed a micro-puffing system for local drug delivery to single cells in electrophysiological experiments, and validated the kinetic properties of this instrument. Based on our results, the kinetics of the delivery of solutions and the territory controlled by this system are influenced by several factors: ( 1) inner diameter ( I. D.) of the guide tubing; ( 2) I. D. of the puffing tip; ( 3) angle of the puffing tip; and ( 4) gravity or external pressure applied to the solution. The system can fully control a territory of 200 x 600 mu m(2). The minimum delay in response to drug delivery is 10-20 ms. Switching between different solutions takes less than 100 ms. The minimum volume of solution required by the system is 0.2 ml. Taken together, our results provide useful data for designing and using an efficient drug/solution delivery system in electrophysiological experiments.