Material
- Tubes 0.65 or 1.7 ml microfuge tubes
- Glucometer (OneTouch Ultra)
- Glucose strips
- A pair of scissors to cut the tails
- Kim Towels and Gauze
- Table of mice for record keeping of values
- Mouse Restrainer
- Heparinized capillary tubes (50 ml)
Fisherbrand Cat. No. 22-362-566
- Optional: heat pad
Procedure
Separate mice the night before collection of blood samples. If random-fed values need to be determined mice are placed into cages with food and water. For the collection of fasting values place mice into cages without food and with woodchip bedding. Make sure that there is no activity in the animal room before and during the collection of samples.
Taking the blood samples: Place the mouse into a restrainer. Cut the tail tip, wipe with a gauze. Use the first drop of blood for blood glucose measurement. Then take an additional ~ 75-100 ml of blood from the tail using capillary tubes. Transfer the collected blood into microfuge tubes on ice. For efficient blood collection, massage the tail by holding it with your thumb and index finger and applying gentle pressure while moving along the tail from the base of the tail to the tip of the tail. Collect the blood drop with the capillary tube and continue until you have collected about 1 1/2 to 2 capillaries. If the mice do not bleed well you can place the mice in the restrainer on a heat pad.
To compare two groups of mice (for example: knockout vs wild type or transgenic versus non-transgenic or treated vs non-treated groups) under as much as possible identical conditions use the different groups of mice the same day and proceed with mice in alternating order.
For example: wild type – knockout - wild type - knockout and so on.
Processing of the heparinized blood sample for determination of insulin in the plasma: Spin the tubes for 10 min at 1600 g in the microfuge at 4oC.
Remove the yellow-red tinted supernatant (about 30-50 ml) and place into a fresh tube. Freeze at -20˚C until processing for RIA for insulin.
We use the RIA from Linco Research, Cat. No. SRI-13K. This is a sensitive insulin RIA. For the measurement of random-fed insulin 10-15 ml of plasma is required and for the measurement of fasting insulin 20-30 ml of plasma is required.
