Satellite cell research earns doctoral student top physiology award

Exercise physiology and biochemistry doctoral student, Karen Martins' work on satellite cell activity in the skeletal muscle of mammals has earned her one of the American Physiological Society's top honours for graduate students. The award, one of four, is one of the most prestigious in the integrative biology sphere and is only awarded once every four years.

Competing against 164 fellow graduate students from around the world at the 2008 Intersociety Meeting on the Integrative Biology of Exercise - V in South Carolina, Martins' abstract, "Nitric oxide synthase inhibition impairs chronic low-frequency stimulation-induced satellite cell activation and prevents skeletal muscle adaptation," was judged to be one of the most outstanding by an international panel of senior scholars in the field of study.

And while the award - $500 travel reimbursement - may be modest, the prestige value in this field of study is immense says Dr. Ted Putman, Martins' supervisor. "This international award recognises Karen as one of the most promising young researchers in the fields of exercise physiology and biochemistry. She is a very deserving recipient. She asks the right questions and is dedicated to maintaining the most rigorous scientific standards in her pursuit of answers."

Martins, who hopes to complete her doctoral degree in the next six to eight months, is delighted by the recognition. "It's quite an ego boost to have my work validated by senior researchers. Secondly, having this award listed on my curriculum vitae will increase my chances of receiving post-doctoral fellowship funding."

Martins' long-held fascination with the minute and intricate world of cellular and subcellular systems in mammals led to her current award-winning research project which looks at the effects of nitric oxide on skeletal muscle, and specifically how muscle adapts to exercise when deprived of nitric oxide.

"I came into this study looking at the effects of nitric oxide on satellite cells", says Martins, describing her research. "They are muscle-specific stem cells involved in skeletal muscle adaptation to both resistance training and endurance training. To date, nitric oxide is involved in the only confirmed satellite cell activation pathway."

Martins decided to see what happened when nitric oxide was blocked. Would an as-yet undiscovered pathway activate the satellite cells? Or would they simply not activate at all?

"I wanted to know how important the role of nitric oxide was in activating satellite cells during exercise because this pathway has only been studied in response to injury," she says.

What Martins found astounded her. After blocking all nitric oxide, then exercising skeletal muscle to exhaustion, she assayed the exercised muscle to test for satellite cell activity.

"I found that satellite cells were not activated during the first two days of exercise, which is what I expected because I had blocked the only known pathway that activates them. By the fifth day of exercise, however, satellite cell activity had fully recovered. This result tells me there's a nitric oxide-independent satellite cell activation pathway at work here that has yet to be identified. It was really exciting to discover not only an alternative pathway, but one that is able to fully compensate in the absence of the preferred pathway."

In some ways Martins says she's not surprised at the body's ingenuity: "All pathways in the body are interconnected with other redundant pathways so you wouldn't expect that there would be one single pathway to activate satellite cells. Until now, however, the nitric oxide pathway was the only single proven activation pathway."

Martins' discovery may give clinical researchers the information they need to make medical breakthroughs. But she won't be at the helm.

"I consider myself a basic researcher," explains Martins. "I build the foundation of basic knowledge about systems and pathways, which allows applied researchers to build their work on my foundation."

"Applied muscular dystrophy researchers may be able to use this finding because satellite cells themselves are a source of dysfunction in muscular dystrophy.

The more I can discover about satellite cells themselves and how they react to different perturbations in the body, the more I can aid applied researchers in real world settings."

Martins also recently won top honours for her presentation on satellite cells at the Canadian Society for Exercise Physiology's annual conference in Banff, Alberta with presentations being adjudicated by leading Canadian scientists. She hopes to be accepted for a post-doctoral fellowship at a university in Europe or Australia when she completes her PhD.