To begin, turn on the local heating unit and the laser Doppler flowmeter. Open a LabChart software file. Next, identify the large visible blood vessels on the forearm's ventral aspect, and mark them with a permanent marker.
Clean the marked area with Betadine followed by alcohol. Place a sterile drape over the sterilized skin and apply ice for approximately five minutes. Then, remove the ice and insert an introducer needle with the bevel facing upwards into the skin's dermal layer at 2-3 millimeters depth.
Carefully advance the needle within the dermal layer and exit the skin around 20 millimeters from the insertion point. Connect the probe to a syringe containing lactated Ringer's solution, leaving the needle in place. Carefully insert the opposite end of the probe into the introducer needle until the semipermeable membrane is close, but not inside of the opening of the needle.
Then, slowly perfuse a small amount of Ringer's solution through the fiber until the solution visibly flows through the membrane's pores. Insert the Harvard Bioscience microdialysis probe into the introducer needle until the membrane is fully inside the dermal layer of the skin within the needle. Next, secure the probe using a finger proximal to the needle.
Carefully withdraw the needle in the opposite insertion direction, and tape the external portion of the fiber in place on the skin. Adjust the probe and tape the external fiber on the skin to prevent displacement of the semipermeable membrane during the experiment.
