A phenomenon known as ischemic preconditioning (IP), in which blood flow to muscle is reduced and then restored, has previously been shown to increase muscle function, especially in the heart.
A new study published online June 6, 2005 in Muscle & Nerve explores the link between the protective effect of IP in skeletal muscles and the substance that triggers hibernation. The journal is available online via Wiley InterScience.
During certain types of vascular or reconstructive surgery, it is sometimes necessary to block blood flow, which may cause tissue damage. This problem might potentially be alleviated if a pharmacological substance was able to achieve IP. Hibernation in mammals is thought to confer cardiac benefits similar to IP. Researchers led by Jinback Hong, Ph.D. of the department of biomedical engineering at the University of Minnesota in Minneapolis, MN, set out to explore whether pretreatment with the chemical that induces hibernation (hibernation induction trigger or HIT) would have the same protective effect as IP in skeletal muscles and the mechanism by which this effect might occur. The study involved removing muscle tissue from 77 pigs, and subjecting it to hypoxia (a reduction of oxygen supply) for 90 minutes, followed by 120 minutes of reoxygenation. The muscles were then divided into several groups that were treated with plasma from hibernating woodchucks (HWP), plasma from woodchucks active in the summer (SAWP), HWP plus naloxone (an opiate receptor antagonist), HWP plus potassium channel blocker, and various control groups. After 30 minutes and 120 minutes of reoxygenation, the HWP group showed significantly more muscle activity, as measured by twitch force, than the other groups. The HWP group was also not significantly different than a control group that was not subjected to hypoxia.