An ethanol vapor chamber system for small animals.

Ethanol vapor chambers have been utilized widely in alcohol research since their introduction in 1971, and implementations of these systems are now available commercially. Here, we present a modification of the chamber that can be built at lower cost and greater simplicity of operation. The six-chamber system for rats has multiple air pumps. Ethanol vapor levels are adjusted with the air flow rate, ethanol drip rate, and dilution with room air, without a heater or fans. Ethanol vapor concentrations are measured with a breathalyzer, using room air to dilute the vapor chamber output into the range of the breathalyzer. Multiple pumps provide backup to ensure animal survival in the case of failure of the primary air pump. Tests in animals demonstrated comfortable and stable elevation of blood ethanol, with tight control of the ethanol vapor concentrations and the ability to select from a broad range of levels. The ethanol vapor measurement was rapid and efficient. The parts cost was a few thousand U.S. dollars. This vapor chamber system features low cost, ease of use, and convenient and inexpensive measurement of ethanol vapor concentrations. The lack of a heater and electrical components that could come into contact with ethanol in our case facilitated institutional approval.