Impacts of ischemic preconditioning on the contractile function of skeletal muscle

Yagao FENG; Suya DENG; Guangxiang HONG; Yuqian WANG

ABSTRACT

BACKGROUND:

Ischemic preconditioning (IPC) can effectively improve the ischemic resistance of skeletal muscle and reduce the necrotic areas during ischemia-reperfusion; However, the impacts of IPC on contractile function of skeletal muscle during ischemia-reperfusion is unclear.

OBJECTIVE:

To investigate the effect of IPC on contractile function of skeletal muscle during ischemia-reperfusion.

DESIGN:

A randomized controlled study by employing experimental animals as subjects.

SETTING:

Tongji Medical College, Huazhong University of Science and Technology and the 252 Hospital of Chinese PLA.MATERIALS The experiment was completed in the 252 hospital of Chinese PLA. Totally 14 healthy SD rats were involved.

METHODS:

A rat right hindlimb ischemic model was utilized, 14 SD rats were randomly divided into control group and experimental group. Control group sustained ischemia for 4 hours and reperfusion of 1 hour. Experimental group ischemia for 5 minutes and reperfusion for 5 minutes, after 3 cycles, ischemia for 4 hours and reperfusion for 1 hour continuously of IPC.The isometric twitch contractile force of the right gastrocnemius muscle was measured as a parameter indicating the muscle functional status during is chemia reperfusion. The changes of creatine kinase (CK), malondialdehyde (MDA) in blood sample and the uptake of 99Tcm-methylene diphosphonate (99TcmMDP) in skeletal muscle were measured after 1 hour of reperfusion.MAIN OUTCOME

MEASURES:

The impacts of IPC on contractile force of gastroenemius and serous CK, MDA and the uptake of 99TcmMDP.

RESULTS:

The muscle contractile force in the experimental group after four hours of ischemia was (14.32 ± 5.05) g or (25.71 ± 7.58) g after one-hour reperfusion, which was significantly higher than 0 g or (4. 73 ± 2.05) g of control group(P ＜0. 05). The serous levelsofCK [(104.85 ±9. 84) nkat/L], MDA [ (3 988.60 ± 455.92) nmol/L] and the uptake of 99TcmMDP [ (56.0± 8.1 ) mBq/g per minute] were significantly lower in the experimental group than control group [CK(136.36 ± 14.50) nkat/L, MDA (6 542.90±536.72)nmol/L, and 99TcmMDP (97.3 ±5.8) mBq/g per minute, P＜0.05, P ＜0.01].

CONCLUSION:

IPC can effectively ameliorate the contractile force of skeletal muscle and reduce the necrotic degree of skeletal muscle. Therefore, IPC has a protective effect on the contractile force of ischemic skeletal muscle.