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Advantages of Retroperitoneal Approach
Approaching the kidney from the back allows easy visualization of
the renal artery and dissection without disturbing the delicate renal vein. By laparotomy, the renal artery lies directly under the renal vein making dissection difficult.
Retroperitoneally, there is no interference with the abdominal organs. By
contrast, in laparotomy the intestines and abdominal contents are exposed and must be defected to the side to allow access to the renal artery and vein. This lengthens the
procedure and exposes the mouse's abdominal cavity for additional heat loss.
There is considerable variability in renal vascular branching among mice.
In some mice, explorations of the left kidney reveal insufficient length of vessel to fit the V-series flowprobe before the vessel branches. Because a retroperitoneal
approach is quicker, it is possible to move on in the same mouse to explore the right renal artery.
With a faster surgery, the animal's physiological state will be more
stable and results will be more significant.
Flowprobe Requirements and Mouse Renal Artery Dimensions
- Weight: 17 - 50 grams (varies by strain and model)
- Vessel diameter: 250 - 550 microns
- Minimum vessel length required (without side branches) for flowprobe
placement: 2 mm
- 0.5PSB Transonic flowprobe with handle
- Transonic T420 Flowmeter Module
Protocol for Retroperitoneal Approach to Left Renal Artery
- Anesthetize mouse and position animal in right lateral recombency.
- Make initial skin incision 1 cm lateral to midline of back.
- Cut through skeletal muscle layer to expose the hylus of the kidney.
- Gently retract the kidney to the left to expose the area between the
kidney and the aorta to reveal the renal artery.
- A 2 mm length of vessel without visible branching is required for
flowprobe placement.
- If the vessel is too short or bifurcates, the incision may be closed
and the animal turned on its left side for exploration of the right kidney.
- Use blunt dissection along the renal artery to isolate the vessel and
clear off fat for proper acoustic coupling of probe.
- Position probe so that the renal artery is in the bottom of the reflector.
- Use a syringe with a flexible catheter tip to deposit SurgiLube jelly
in air spaces of probe and verify good transmission of the ultrasound signal by checking the flowmeter "Test" mode. Stabilize probe position with a
micromanipulator for continuous measurement.
Acknowledgements
T.L. Smith, PhD, M.F. Callahan,
PhD, Department of Orthopedic Surgery, Department of Pharmacoloy and Physiology, Wake Forest University Medical School.
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Measuring Renal Flow in Mice 
