Elevated myoplasmic calcium in exercise-induced equine rhabdomyolysis.

The research indicates that heightening levels of intracellular calcium (Ca2+) in horses with exertional rhabdomyolysis, a muscle-related disorder, are more than in horses without the condition. Using a drug called dantrolene, which restricts calcium release, brought the calcium levels closer to normal and sped up recovery from this disease.

Exertional Rhabdomyolysis and Intracellular Calcium Level

• The researchers studied a common muscle-related disorder in horses known as exertional rhabdomyolysis or “tying-up.” The precise cause of this disease is unknown, however, the elevated intracellular resting calcium concentration ([Ca2+]i) links specifically to this condition. They determined this by using Ca(2+)-selective microelectrodes to measure [Ca2+]i in muscle fibers from horses experiencing rhabdomyolysis and horses with no signs of neuromuscular disorder (the control group).

Finding: Heightened levels of Calcium in Rhabdomyolysis

• The results showed that the intracellular resting calcium concentration was several times elevated in muscle fibers from horses suffering from rhabdomyolysis in comparison to the control group, indicating a relationship between [Ca2+]i and this muscle disease.

Treatment with Dantrolene

• The team then treated horses suffering from rhabdomyolysis with dantrolene – a drug that inhibits the release of calcium from the sarcoplasmic reticulum (a structure found within muscle cells that is responsible for storing and releasing calcium).
• The use of dantrolene led to a decrease in [Ca2+]i towards the values observed in the control group. That suggested that dantrolene could play a crucial role in treating rhabdomyolysis by reducing increased intracellular calcium levels in these horses, while also speeding up their recovery from the disease.

Significance of the Research

• This research implicates elevated [Ca2+]i as a characteristic of a rhabdomyolysis attack, providing insight into the possible pathophysiology of the condition.
• In addition, this study highlighted a potential therapeutic approach to mitigating exertional rhabdomyolysis in equine species by using dantrolene, opening new potential horizons for the treatment of this muscle disorder.