Merryl said:

Does anyone have experience with using automatic blood samplers for PK studies on rodents?

I don't have experience in using the sampler but it is highly recommended due to the following reasons:
1-The sampling process is less painful for the animal which reduces stress and improve data.
2-Quality assurance is improved because of sampling and volumes are precisely controlled.
3-The combination of 96 well plate sample preparation with LC-MS-MS makes the procedure feasible for big pharma.

Check CulexABS automated blood sampler at www.culex.net