Abstract: Objective To explore the expression and the changes of microtubule, aquaporin-4 (AQP4) and potassium ion channel 4.1 (Kir4.1) after spinal cord injury in rats.Methods Ninety female adult Sprague-Dawley rats were randomly divided into sham operation group (n=30) and injury group (n=60). The injury group was divided into six hours, one day, three days, five days and seven days subgroups, with twelve rats in each subgroup. Spinal cord injury at T₁₀ was established with modified Allen's method (20 g×25 mm) in the injury group. The water content of spinal cord was measured at each time point after injury. Then, the pathology was observed with HE staining, the expression of α-Tubulin, AQP4 and Kir4.1 was detected and analyzed with immunohistochemical staining and Western blotting.Results The water content of the spinal cord was higher in the injured group than in the sham operation group (P<0.05), and was highest on the fifth day. HE staining showed that the gray matter hemorrhage at six hours after injury; one day after injury, the gray matter bled seriously, and neuron swelling was aggravated; three days after injury, the area of gray matter necrosis increased, and the edema phenomenon was obvious; five days and seven days after injury, the gray matter necrosis and the edema phenomenon were more serious. Western blotting and immunohistochemistry showed that the expression of AQP4 gradually increased after injury, and raised at peak on the fifth day; the expression of α-Tubulin and Kir4.1 was similar, and the expression gradually decreased after injury, especially on the fifth day.Conclusion The expression of α-Tubulin and Kir4.1 is similar after spinal cord injury, and is contrary to the expression of AQP4. α-Tubulin, AQP4 and Kir4.1 may be related after injury and may participate in the formation of spinal cord edema.

Key words: spinal cord edema, microtubule, aquaporin 4, potassium ion channel 4.1, rats