Myostatin Inhibition Does Not Affect the Heart
When myostatin was first discovered, researchers questioned although myostatin inhibition results in increases in muscle mass, does it affect the heart? To date, there are no long-term studies of myostatin inhibition in humans, but Belgian Blue cows appear to have smaller hearts and a shorter lifespan, whereas whippet MSTN knockout dogs are actually slower than their leaner greyhound relatives. In a recent issue of The Journal of Physiology, researchers systematically explored the effect of myostatin inhibition on cardiac structure and function. The authors used a myostatin knockout mouse model with ∼30% increase in body weight (due mainly to skeletal muscle gain) and similar increase in cardiac mass. Thus, body weight/heart weight ratio of MSTN knocjout mice was no different from wild-type littermates. Overall, the cardiac effects affirm the notion that myostatin inhibition generates a ‘mighty mouse’ with no apparent deleterious cardiac effects. The authors studies support the novel concept that myostatin is a repressor of physiological cardiac muscle growth and function. Thus, the controlled inhibition of myostatin action could potentially help repair damaged cardiac muscle by inducing physiological hypertrophy; although caution should be exerted because no functional analysis of other organs was conducted, and long-term effects remain unclear. Human studies need to be conducted but the fact that myostatin had no effect on heart mass or function leads to further support for myostatin use as a safe and effective means for increasing muscle mass.