Serial determination of plasma ethanol concentrations in mice

A technique permitting the serial determination of plasma ethanol concentration (PEC) in mice is described. Samples of blood, 5 microliters in volume, are drawn from the infraorbital plexus. It was demonstrated that this source reflects the rapid dynamics of absorption and clearance after an intraperitoneal injection of ethanol. Samples taken from the tail showed a greatly delayed response and required 30 min to equilibrate with samples taken from the infraorbital plexus. The concentrations of ethanol were determined by gas chromatography. A precolumn removed the nonvolatile constituents thus permitting the injection of plasma directly into the instrument. The ratio of ethanol concentrations in red blood cells to plasma was found to be 0.62. This permitted the estimation of concentration of ethanol in whole blood: (1-0.38 H) X PEC; where H = the hematocrit.