Can saline be used in place of blood to perform a cuvette volume calibration?
A common method of calibrating a conductance measurement into volume units is to perform a cuvette calibration using blood. Ideally, this calibration should be performed before each experiment to take into account the ability of the rings to measure conductance (which can change from day to day depending on cleaning and maintenance of the catheter). For some species, it might be feasible to withdraw a large enough sample to perform this calibration before every experiment; however, this is not possible with small rodents. Typically, a small subset of animals is used to establish a calibration curve. These calibration values are then applied to data collected for the rest of the group. Some labs will simply perform this calculation when a catheter is used for the very first time. There is a way to calibrate the catheter before measuring from EACH animal without withdrawing any blood. Blood has a specific resistivity which is important in solving for volume using Baan’s equation. Any oth
