快猫短视频s have found an enzyme in muscle that, when activated, can mimic the effects of exercise. The discovery could one day lead to 鈥渆xercise in a bottle鈥� pills but this will not be for many years, as the experiments have so far only been done in mice.
But the new research singles out a promising target in the intense search for drugs that give people the benefits of exercise without them even lifting a finger. The target, an enzyme called calmodulin-dependent protein kinase (CaMK) causes muscle to behave as if it has been exercised.
Such a drug would not just be an elixir for the lazy, it would improve the lives of chronically ill patients who would benefit from exercise but cannot tolerate the exertion. It might even have applications for athletes looking to gain muscle endurance.
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鈥淭his opens the doors to drug discovery,鈥� says R. Sanders Williams, dean of Duke University School of Medicine, who lead the research with colleagues at the University of Texas Southwestern Medical Center in Dallas. He would not say whether he has any candidates in mind, but pointed out that drugs exist that inhibit the activity of CaMK, so finding one that activates it instead might not all that hard.
Energy factories
Williams discovered the enzyme鈥檚 unique abilities after engineering mice to make high levels of CaMK in muscle. Even though the animals had not been exercised, their muscles behaved in many ways as if they had.
For example, many muscle fibres converted into the 鈥渟low-twitch鈥� kind, which has special properties and is abundant in muscle accustomed to chronic exercise. And the muscles were better at resisting fatigue during repetitive contractions.
The muscle cells also sprouted high numbers of mitochondria, the tiny energy factories of cells. This is known as mitochondrial biogenesis and for years has been considered an important hallmark of the response of muscle to endurance exercise.
Mystery solved
Exactly how exercise leads to this spike in mitochondria had been a mystery for decades, and CaMK now offers an answer, says exercise biology expert David Hood from York University in Toronto: 鈥淭his is the first paper that really shows the link.鈥�
鈥淚t makes a lot of sense,鈥� he says, because CamK is a protein that responds to calcium. 鈥淓very time a muscle contracts, calcium is released and elevated in the cell.鈥� The calcium then activates CamK, which triggers the medley of effects in the response to exercise.
It is not far-fetched to think that a drug that activates the enzyme in people鈥檚 muscle could be used to 鈥渆xercise鈥� their muscles without exercise, says Hood.
Journal reference: Science (vol 296, p 349)