Study identifies potential new treatment target for sleep apnea: A recent mouse study shows the target is an ion channel already proven to affect blood pressure in obese mice

In a new study with obese mice, Johns Hopkins Medicine researchers say they have added to evidence that specialized channel proteins are possible therapeutic targets for sleep apnea and similar abnormally slow breathing disorders in obese people.

The protein, a cation channel known as TRPM7, is found in carotid bodies, tiny sensory organs in the neck that detect oxygen and carbon dioxide changes, and certain hormones such as leptin, in the bloodstream. TRPM7 proteins help transport and regulate the stream of positively charged molecules in and out of the carotid bodies’ cells.

The new research, carried out in the Johns Hopkins Medicine Polotsky Research Lab and led by postdoctoral fellow Lenise Kim, Ph.D., builds on previous findings from the lab that show that TRPM7 contributed to the development of high blood pressure in mice.

The latest experiments, described in a report first published October 10 in The Journal of Physiology, revealed that TRPM7 plays a role in suppressing breathing in obese mice with symptoms of sleep-disordered breathing conditions.

Sleep-disordered breathing is characterized by breathing that stops and starts throughout sleep and is estimated to affect up to 45% of obese Americans. Untreated, the condition can worsen heart disease progression and diabetes, cause significant fatigue, as well as death from poor oxygenation. Lifestyle changes such as weight loss and nightly use of continuous positive airway pressure devices, or CPAP, can alleviate sleep apnea, but CPAP treatment is often poorly tolerated by patients.

“CPAP actually works for most patients, the fact is that most patients are not adherent to this treatment,” says Kim. “So knowing that TRPM7 contributed to high blood pressure and sleep-disordered breathing, we wondered if blocking or eliminating that channel could offer a new treatment target.”

Using silencing RNA, the researchers knocked out the gene responsible for the production of the TRPM7 channel protein, reducing the number of TRPM7 channels in the carotid bodies of obese mice. Mice then underwent a sleep study, during which researchers observed their breathing patterns and blood oxygen levels.

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