Place a dark-adapted, anesthetized rat with healthy muscle tone on a heating pad.
Apply artificial tears to prevent corneal drying.
Extend one hind limb and secure a temperature probe to the footpad to continuously monitor skin temperature.
Wrap a deflated blood pressure cuff around the upper hind limb.
Inflate the cuff to the desired pressure to restrict arterial blood flow, inducing ischemia.
Immediately begin temperature recording. A decrease in temperature indicates reduced perfusion, confirming arterial occlusion and ischemia onset.
During ischemia, oxygen deprivation activates cellular stress pathways, triggering the release of neuroprotective factors.
These factors enter circulation and help protect distant organs, such as the brain and retina, from subsequent injury.
Maintain the pressure for a set duration, then release the cuff for reperfusion. Repeat the ischemia process to enhance systemic protection.
Finally, fully deflate the cuff to restore normal blood flow and allow the rat to recover.
After dark adapting the animal according to the text protocol, confirm that it has good muscle tone by pinching the upper hind limb to confirm that there is adequate muscle present. After sedating the animal according to the text protocol, check the depth of anesthesia by extending the leg and pinching the skin on the underside of the foot. Then apply artificial tears. Place the rat on either a heating pad or circulating water heater tubing in a prone position, with the foot pads of the lower limbs facing up.
To apply the skin temperature probe, extend the leg of the rat that will undergo ischemia. And firmly place the skin probe on the pad, positioning it to maximize contact between the temperature probe and the skin. Then use paper tape to affix the probe. Check the skin probe placement by tracking the temperature on the temperature recording software for one to two minutes. Ensure that the skin temperature is between 30 to 34 degrees Celsius and remains stable. Otherwise, adjust the probe.
To carry out remote ischemia, begin with a deflated cuff and ensure the air pressure valve is closed. Extend the leg and loosely encircle the cuff on the upper hind limb. Use the forefinger and thumb to extend the leg and the lower digits to keep the loosened cuff in position. Now, raise the cuff pressure to 160 millimeters of mercury. Once the correct pressure is reached, start the timer and foot temperature recordings.
The foot temperature should drop by two degrees Celsius after five minutes of constant pressure. Repeatedly pump the inflation bulb in short bursts to maintain the desired cuff pressure and maintain the position of the cuff above the animal's knee throughout the ischemia. Continuously deliver remote ischemia for five minutes. Then release the air pressure valve for a five-minute reperfusion before repeating the remote ischemia.
When the procedure is complete, deflate the cuff pressure by loosening the air pressure valve. Check the temperature change over the course of the ischemia protocol. Then release the cuff. Place the animal on a heating pad and continue to monitor until ambulatory. When the animal is walking, return it to housing.
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