Ca2+ sensitizers: An emerging class of agents for counterbalancing weakness in skeletal muscle diseases?

Ca2+ ions are key regulators of skeletal muscle contraction. By binding to contractile proteins, they initiate a cascade of molecular events leading to cross-bridge formation and ultimately, muscle shortening and force production. The ability of contractile proteins to respond to Ca2+ attachment, also known as Ca2+ sensitivity, is often compromised in acquired and congenital skeletal muscle disorders. It constitutes, undoubtedly, a major physiological cause of weakness for patients. In this review, we discuss recent studies giving strong molecular and cellular evidence that pharmacological modulators of some of the contractile proteins, also termed Ca2+ sensitizers, are efficient agents to improve Ca2+ sensitivity and function in diseased skeletal muscle cells. In fact, they compensate for the impaired contractile proteins response to Ca2+ binding. Currently, such Ca2+ sensitizing compounds are successfully used for reducing problems in cardiac disorders. Therefore, in the future, under certain conditions, these agents may represent an emerging class of agents to enhance the quality of life of patients suffering from skeletal muscle weakness.